Hi. We really enjoy doing an organized tour in the spring as a way to aid in training, and get in some hill work, before taking a self-contained tour in the late summer/early fall. It's nice to let someone else do all the planning, especially when overseas. We have used Backroads(3), REI Travel(1) and VBT(2). The cost per day, high to low, is in that order as well. With Backroads' "Premier" designated trips you likely will have a dinner or two in a Michelin starred restaurant, stay at fabulous resorts and have some great cultural excursions. However, don't think that the amenities with the other two organizations are in any way deficient as they are not. In fact, the other people on the trip and the guides have a larger impact on the enjoyment of the trip, and in that regard we rank the VBT trips highest. That said, Backroads having a professor from the University of Bordeaux come and give us a lunchtime talk on human evolution before personally taking us through the caves at Les Eyzies to view the pre-historic paintings has been the singular most memorable and moving event of our trips.
Here is a web site that you can use to compare various companies.
Bike Tour Reviews.
Good Luck,