Welcome to the club!!
You will not regret switching from a canoe.
I’d definitely recommend not going less than a 14’ raft.
I’m a huge fan of Aire boats but there’s a lot of good ones out there. For the money, Aire is hard to beat. The Tributary is a solid all around boat. I run mine on everything from the Lochsa to the Grand Ronde and Salmon and everything in between, day trips or multi day trips, it’s been fantastic.
I know you said you were looking for used but you should check out the Star outlaw boats. NRS has them new for around $2500. I’m super impressed with them.
Anyway, you didn’t post asking for my opinion, I’ll keep my ears open for a good deal and talk with some of my rafting buddies.
Good luck and congratulations!