Competitive trail would be fun.
The people are the best, the horses are always nice, and the trails are breathtaking! It's a great escape from everything. Also, prep work is pretty straight forward. Your horse has to be in some shape (most horses can do a one day, 15 mile ride without much conditioning), you must be able to mount without her moving, sidepass (sort of optional, but very good for your score cards), and cross logs/creeks/ditches. That, plus some basic trail sense, will be all you need for a novice one-day ride.
Seriously, check it out!