While I enjoyed Ethan of Athos, I expect some people may not care for the gay protagonist. It is for this reason that I suggest starting with one of Bujold's other books, especially The Warrior Apprentice.

While I enjoyed the Hitchhiker's series, I found the Dirk Gently books to be even better. The stories seem to be less disjointed - they don't jump around as much, and stick to a more straightforward storyline. Not that I'm suggesting that the Dirk Gently books are in any way predictable. Far from it, but I think they might be a better starting point for Adams's work.