A tall, calm dog for Penny?

As soon as I get a job down in Sydney, me and the furry family are moving in with my boyfriend permanently. He'll be buying a house with a little yard so we can keep Penny happy and he's agreed to help me take care of an extra dog once we settle in. Some of you might know that I've been more or less set on akitas for a while, now, and that's rather what I think my next dog will be.

I've had some pause for thought, though, based on recent health developments with Penny.

Firstly, she's eleven, now, and while she's fantastically fit and trim for her age, I am starting to see signs of old age creeping up on her. She's got some clouding in her eyes and in recent times, it's clear she's slowly going blind. At the moment, it only manifests itself in her tripping up on things like sticks and tree roots because she doesn't see them, but I realise it's most likely going to get gradually worse. It doesn't bother me, because Penny will learn to cope with it as her sight deteriates, but I am a little concerned about bringing a puppy into her life if her sight isn't real great. I don't want to get an adult akita from rescue partly because I don't want to bring a potentially dog aggressive dog into my family when it could kill Penny with a shake, and partly because I'm nervous about bringing any adult dog into my family because of the rabbits. I think it's unfair to expect a dog that hasn't been brought up with rabbits to think anything other than that they're a great thing to chase and bite, especially a large dog with a fair amount of prey drive.

So I'm caught in this dilemma. I want a puppy for the bunnies, but an adult dog for Penny. I'll be keeping an eye on the local shelters for the right kind of senior dog to come up, but I'm not confident I'd find a dog right for all the members of my family as well as me. I thought maybe I should forget the idea all together and wait until Penny isn't with us anymore, but I love the dynamics of two dogs and Penny is pretty mopey on her own, especially when everyone is out working all day. When she was living with my housemate's old dog, she was so relaxed about being left in the yard all day, and it was so cute when Raz would whine at my door at sunrise, asking if Penny could come out and play. It was nice to see them hanging out all the time.

Recently, we all met up with a friend while walking our dogs. The friend has a rescued greyhound that she got a few months ago. We did our hour long loop together and Penny just loves this greyhound. She walked the whole way around practically under the greyhound's belly. She seemed to think it was cool that she couldn't reach the greyhound's nose even if she reached up as far as she could. She also seemed to appreciate the greyhound's calmness and passive companionship. Both of them looked sad to part ways at the end of the walk.

So, I'm wondering if anyone knows of a breed that's both nice and tall, and tends towards being very laid back and calm? I'd go straight for a rescue greyhound if it wasn't for those rabbits. I know you can get greyhounds that are good with small animals, but I don't know that I'd be so lucky to find one. Any ideas?