Yep, Road 18 is where most people camp, but there are some pay spots on the river around there. Road 18 & Kokopelli Loops are night and day. Road 18 is smooth tight singletrack, Kokopelli slower technical, ledgy. I thought Chutes & Ladders was a pretty fun roller coaster ride in the Road 18 area so long as you're comfy getting your butt over the rear wheel for steep smooth descents. You can actually do all the Road 18 trails in a day though.
Be sure to ride Horse Thief Bench in the Kokopelli area. You might want to walk the entrance, but most everything else is rideable. Moore Fun has some nice technical challenges.
If you have 3 days, check out the Lunch Loop trails in GJ. Don't miss Holy Cross (dowhill).
You can find good maps in bike shops around the FR too.