...what changes would you make, if any?

I would have explored Trappers and Franks relationship with their wives more, kept Duke from the book and the movie and made Trapper the chest surgeon and chief surgeon like he was in the movie and book. (I should say the first book; since there were a few sequels to it).

I'll agree to expanding Trap. I'd also try to find some way to keep Spearchucker.

Um, and I'd re-write half the first season's episodes to be less slap-sticky and as smart as the later seasons :)