I have mentioned this before in another thread, but I will put it here aswell. Have you entertained the idea of a rescue greyhound? They are a large breed ranging 40-60lb, easy to train, strive to please, have low grooming requirements, many people with dander issues do well with them, and indoors are couch potatoes. They do however require daily exercise, but nothing more than a bike ride around the block once or twice.
If anyone has a different experience with them in this situation please speak up. But to me, it seems they would be aa good fit. There are hundreds of greyhound rescues, so you would have a large variety of choice to find that special companion.