As owner of a german shepherd who weighs in at over 32kg (70 lbs), I can safely say that they are a lot of work! Lucy needs a good amount of exercise (which I can now do properly as I approach my target weight!) and is pretty bright, so we play a lot of games with her to keep her brain stimulated. Mere is right about big dogs sometimes having hip problems, german shepherds in particular are susceptible to hip dysplaysia and most dogs are hip scored before breeding.
We had a labrador when I grew up and he was the happiest, but stupidest dog I've ever known! He could eat for England and could smell a biscuit at 50 yards, and he had a wonderful temprament. The breed like chasing/fetching games as well as swimming, and would certainly like games where you can throw floats into water for them to bring back to you. They really are lovely though, very loyal and friendly.
Another side to having a larger dog is the increased vet fees- larger dogs need more antibiotics if they have an infection, for example. It might be worth you getting some insurance for that, if it's available in the US.
Other than that, the poos are bigger, there's more hair and you can't pick your dog up and put it in your handbag, but I wouldn't swap my large dog for anything smaller. Plus, she scares the living shit out of anyone who comes to the door, she's a fantastic guard dog
