I have two Chow Chows. One of them, Leela, is a four year old rescue who is just great with the bunnies, but that's becauseI made sure to introduce them properly. Any sign of excitement was NOT tolerated, and I did the intro slowly over about a month before they were ever allowed to touch each other. As the alpha, I had to show my dog right from the start that bunnies are not toys, they are members of the family. I would trust Leela alone with the rabbits because she is so low energy and has met the rabbits properly. Molly has even gone so far as to hump Leela for dominence, and Leela just lays there and takes it :biggrin2:.
My younger Chow, Duke,is still just a puppy, only three months old. Because he's a pup, he still gets a little too excited about things and when he sees the bunnies, he wants to play with them. I only let him interact with the bunnies through the bars of their pen. By interact, I mean sniff, which is the best way for him to get to know them. Any pawing or whining is met with a stern NO, and he is put into a down-stay until he calms down (which can take 5 or 10 minutes. He will likely not be trusted alone with the rabbits for another year or so at least.
I think a lot of it does have to do with your dog's breed, and a lot of it has to do with how the dog's view you in their life. If you are the "leader", they will listen. But, if for any reason you hesitate to leave your dogs and bunnies alone together, their playdates should probably be supervised. After all, dogs are natural predators, and rabbit's are natural prey.