Upvote:2
I have only been to Sedona a few times but Slide Rock and Hiking are the only two suggestions I have.
If you like cliff jumping or swimming Slide Rock is a great place to start. http://azstateparks.com/Parks/SLRO/index.html
Also, there is a ton of hiking and things to see. There are several great references through a google search. Unfortunately I always had a local or guide so I can't tell you exactly where I went myself but the entire area is beautiful. http://www.greatsedonahikes.com/