The Crate....the stupid crate...

I timed it this morning, in fact, at an hour and a half before I gave up and let her out.

Yes, and if your roommate continues to let the dog out every time it whines, this is intermittent reinforcement, and the behavior will get worse.  When I crate train my dogs (they are therapy dogs and must travel a lot, so I teach them early to crate so they can ride in crates in my SUV), I make sure they are fed, watered, and later toileted.  Once I put them in the crate, I ignore any barking or whining.  If they are quiet for 2 minutes, I tell them "good quiet" and they get to come out.  With puppies, I set my alarm to take them out for the midnight potty run, but I don't talk to them (other than to say "go pee"), I certainly don't play with them, and I put them right back into the crate without fuss and turn off the light again.  They learn the routine, and soon are just going back in because they know that I don't give in.  Of course, they are properly acclimated to the crate from the get go, and they have plenty of companionship and play with me during daylight hours.
 
Crates are not necessary, else how did anyone housetrain dogs before we had them?  But, they are useful to keep dogs safe (especially in the chewing stage), and the dogs seem to like having a secure, safe place to go for naps and to get a marrow bone or a stuffed kong toy.

In addition, intermittent reenforcement issues notwithstanding, I'm worried that if I try to 'force' the issue on her, it may encourage a relapse in other behavior issues.  And again, aside from the crate issue, she is a miraculously well-adjusted and -behaved puppy. 
 
 

I never "force" a dog into a crate.  If you make it a fun place to be, and start small, she will adjust - but you do need the cooperation of your roommate.  If you prefer to confine her to the kitchen, and there is someone always there to supervise her, it's fine.  But, be aware that even if she is great now, she will come to the chewing stage after her adult teeth are all in, and she may decide (since they "must" chew to set those teeth into their jaw bones) that your kitchen table legs are a wonderful chew item.
My mom raised tons of dogs with no crates, but someone was always in the home watching them.  It's harder if you have to attend classes, or work.

Are you crating her for a specific reason? If not then why not just stick with the kitchen idea? I personally dont crate my dog because she is "the dog of the house" and ots her domain. Instead I focused on training her to behave in the house as to what fits my lifestyle. If you are crating her because thats is the way you want her to live and behave then that is understandable but who's dog is she really Who gets the dog when you two move out? That is the deciding factor in which way goes. I agree that you two need to employ the same raining techniques otherwise its horrible for the dog. Maybe some better communication between you and your roomante will be helpful, dont be shy either becuase the one who will suffer in the end is the dog. Good luck with your pup!

What are your long term plans for your dog? Do you want to crate her when she's alone or is this more a temporary situation until she is older and more trustworthy. I personally only used a crate until my dog was able to hold his bladder through the night. At that point I set him up in our mud room so he was not wandering around while we were sleeping. If I had to leave during the day I would again put him in his room until I got back. By 8 months, I was able to leave him free when I went out (2 or 3 hours) and by a year he had free run 24/7. As Anne pointed out chewing can be a problem with an unsupervised pup. I always made sure he had lots of things he COULD chew on and was very diligent in training him not to chew inappropriate items.

I am a strong believer in training your dog to live the way you want from the get go. If you want your dog to be in a crate during the day and/or night, that's what you do. If you want your dog to have free run of the house - then you start training him according right from the start. Personally I am not a big fan of crating, but lots of idoggers do it and swear by it. It's up to you as the dog owner to decide what you want for your dog. The most important thing is to make up your mind and stick to it. Otherwise you are setting your girl up for failure.

From experience, I can tell you that what your roomate is doing, taking the dog out and sleeping on the couch with her, will create a problem, or well, it depends on whether or not you view it a problem. She'll whine every night because she'd rather sleep with someone than alone, and she'll figure out pretty soon that whining gets this. I solved the problem by not putting my dog in his crate at all at night, and just having him sleep in my bed. If you don't want a problem, your roomate's gotta stop doing that. 

Yup that works to but not everyone wants their dog in their bed. My girl sleeps at the foot of my bed and is fine with her limited space. They can also be trained to just sleep next to your bed on their own bed but at the very least make sure when he is in his crate that he can see one of you. A pack instinct inside of a dog tells them that if they are seperated from the pack they are dead meat! Have you tried that?

First of all, I want to thank you all for your prompt willingness to try to help out. 
 
To address a few specifics, then:
 
--We have discussed, she and I, many times in the past, that when / if we ever got a dog, when the two of us inevitably parted ways, the dog would go with me--for no particular reason; just to resolve the issue before it arose.  Now, though, more than ever, I am convinced that that's the way it'll have to go.
 
Initially, I thought the kitchen thing was working wonderfully, and I only gave into the crate idea because practically everyone around me--including the roommate and the vet--told me to.  I now admit I should held my ground.  What we're doing at this juncture is: she sleeps in the crate at night, and stays in there when no one is home.  She's a good dog, and she knows, rather well already, what she can and cannot chew; but, she's still a puppy, and there have been many I'm-just-going-to-the-shower-she'll-be-fine-oh-my-god-what-did-you-do?!? catastrophes. 
 
And the kitchen, though, again, I thought was wonderful (the puppy loved it, most importantly), but it won't work anymore.  We don't have a baby gate thing, and there's no way to close off the kitchen from the back hallway, a decisively no-no area.  In the beginning, I just stacked boxes she was too big to get over to block the hallway off.  I figured that when she got big enough to physically climb/jump over them, she would have already learned she wasn't allowed to; which worked, at first.  Then she got ticked off one day, took a stab at it...long story short, won't work, not unless / until I buy a baby gate. 
 
And I'd love for her to be able to sleep in my bed, but she's mostly rottweiler, and I'm concerned about her developing dominant tendancies (sp).  I can already see a difference in her level of assertion with me versus with my roommate: she sees me as the boss, she sees the roommate as another member of the family.
 
And I know I'm longwinded, and perhaps I talk in circles; it's just I haven't had a dog in over 10 years, and I really want to raise her right.  She's turning out great so far, for the most part...I'm just paranoid about her developing some major personality defect, or whatnot.    

Hi and welcome!!  If she is your dog (and if she is going with you when you and your roommate no longer live together - then she is your dog) - then, you need to set the rules, but you also need to follow through if your roommate won't.  I suggest moving the crate to your bedroom and taking it upon yourself to crate train the dog to sleep through the night.  It may mean a bunch of sleepless early mornings, but there is no way to do this without consistency.  If your roommate wants to keep up the every other day thing and is going to participate in raising the dog, it has to be done consistently with your methods.  If your dog is clawing and barking to go to the bathroom - I might try taking her a little earlier, when she is still sleepy - straight out to go potty, straight back in, no fuss, no playing...  maybe then she will sleep longer.  If that is not it - honestly, you have to just ride it out - never let her out until she is quiet...  It will likely get worse before it gets better - but eventually it will work...  Good luck!!