The apartment thing is no fun with breed and weight restrictions. You probably don't want a toy breed so I suggest you keep an eye out for border collie or husky type mixes that can get quite tall but stay lightweight at the same time. I actually met a rescue dog at the dog park one day that was up for adoption. She was a brindle pug mixed with some sort of terrier and about 18 inches tall and only 23 pounds. She looked like a stretched out, skinny pit bull. She would have been perfect for an apartment if I was looking at the time. I hope to find another like her when my old dogs are no longer with me, assuming I'm still in an apartment.