I made the opposite move about four years ago. Grew up rafting and kayaking most rivers in CO.
Fort Collins is an awesome town and the Poudre is a GREAT little river. Looks like the entire state is poised for a pretty good season...so at least you picked a good time to move there!
Everything starts running a bit later in CO (mid-Mayish). Although some early season options could include Cross Mountain Gorge, the Royal Gorge on the Ark, the Piedra, Shoshone on the Colorado by Glenwood Springs is almost always an option.
Some awesome overnight trips that I always enjoyed were Browns Canyon on the Ark (typically a day trip, but a nice over night too...similar to Cabarton with a lot more whitewater and better scenery). The Pumphouse run on the Colorado river...although this one can get pretty busy. Gunnison Gorge is a good one. IMO the best over-night raft trip with the best whitewater, scenery, and overall experience is the Upper Animas down by Silverton.
Welcome to the land of daytrips...too many to list. A good starting point is just up the road, the Poudre has a few awesome sections...Rustic, Stephens Gulch. Head over to Buena Vista (which is the whitewater hub of the state) and the Arkansas has a LOT of great stretches, PineCreek/Numbers, Fractions, Browns Canyon, Pinnacle/Parkdale, The Royal Gorge.
Big water???? Nothing like what you're used too...rivers in CO are steep, fast, and technical. They can get huge features/holes, etc....but a totally different type of "big water" than Idaho rivers. Tons of fun...just different (lets put it this way...a HUGE year on the Arkansas which happens maybe once a decade is 5,000+ cfs).
A 12' WD will kick ass...perfect boat for most rivers down there!