Some tour companies
Bicycle Tour of Colorado
Colorado Rocy Mountain Bike Tour
PacTour
America by Bicycle
Cycle America
Western Spirit
Adventure Cycling

I'd recommend trying to do the Icefields Parkway in BC or Pacific Coast of the USA.

I've never done a long supported tour, only week-long ones, they are pretty fun but I do think that they get expensive really fast, so if you want to maximize your dollar/mile on a longer trip, and are willing to carry your own gear, purchasing equipment for self-supported trips is worth it. Once you buy the gear, you'll have it for many years, so you can amortize the cost of the equipment over that, instead of paying for one experience.

You could also do a "credit card tour" - where you just carry clothes and stay in hotels - if you have the $ for that, it can be really fun. COst does add up pretty quick, but if you don't like camping, it's totally do-able. You can put a light rack on your road bike, and just plan your own trip.