I'm with Eden on the rain pants and the rain jacket.
How early this spring in this ride? It could still be pretty chilly in Wyoming depending on how early it is. If that's the case, I would bring a good all purpose jacket rather than a soft-shell rain jacket. I love the Gore Passion Plus jacket that I have.
I don't wear bibs and can't speak to them. I have a small bladder so I'm not sure I'd like having to deal with them.
Having gone on some tours myself, one suggestion I have it to pack your clothes in smaller plastic bags. For one, it helps keep things organized. For another, it's another barrier to moisture. Even without rain, everything tends to get damp (assuming you're camping).
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher