Regarding size I think it boils down to what your going to use it for the most. I have the 42" and it's a bit to lug around, and I'm 6'4". It can get a bit crowded ringside at a trial, so having a smaller crate will need less room. There are times I wish I had a 36", as it would be easier to carry around, and Brooks would fit in it just fine. But, I do use it for both dogs at times, so having the 36" wouldn't work. I think having the bigger size does allow Brooks to stretch out which does make it a bit more comfortable for him.