Are you thinking road or moutain?

My hubby and I take a supported mtb tour every year. Even if you don't mtn bike, there are mountain bike tours geared to roadies (i.e. less technical riding). The very 1st tour we took, we rode from Telluride to Moab in 6 days. It was glorious and I would do it again in a heartbeat. You feel like you're on top of the world up on those plateaus. We've been on mtbike tours all over the west (red rock canyons, to pinon forests, to high desert). We'll also go someplace and do our own rides every day. Bend, OR and Ketchum, ID are both good places to stay and plan your own mtb rides at all levels of abilities.

Escape Adventures (tour company) is located in Las Vegas and has rides all over the place.

If you're looking for road riding, I would highly recommend northern CA in the spring (late March to May). The wildflowers can be spectacular. Plus, you can find good cheese and wine!