That would have been the Trans America. Since I have already done it, with my daughter no less, I am not sure if it still qualifies. In any case I generally think of various US destinations when I think about "dream tours". My current dream tour is the Sierra Cascades route that I am planning for this Summer. Others are the Pacific Coast, the East Coast, and a number of routes in the Rockies.

OTOH, I guess my dream trip isn't really a trip but the ability to do a longish tour every year or so. I wouldn't limit that dream to bike tours though. Backpacking, kayaking, sailing, and journey running could all scratch the same itch for me.