I went with Sports Tours International in 2009 and did the entire tour. It was fantastic and I'm going again in 2014.
The only thing I didn't like about STI was the guides we had were Californians and were of the classic American type that seems to think the world is there to serve them. They didn't speak one word of French (after doing it for about 6 years) didn't have a shower on our bike trailer as I saw on other tour buses but that might have a bit to with their prices.
The good thing about STI was as they're an international outfit the tour group was from all over.
Our coach had Americans, English, Welsh, South Africans, New Zealanders and Australians which made it all the more interesting.
The hotels were all 4 or 5 star and the food was also great. We always had brekky, and most nights there was dinner included.
A couple of nights we stayed in the same hotels as one of the Teams which was absolutely a bonus.
When we got to Paris there was a great meeting of the tour groups and STI seemed to have thousands of clients. Our tour leaders seemed to be the exception as everyone else I met had a great time with their guides.
Next time I go I'll either use them again or Bikestyle who seem to have a very professional set up and their guides are super good.
My tip is definitely go with an organised tour though, as all you have to do is keep yourself organised, and the tour organisers do the rest.
They also have a bit of inside info on how to get some extra perks out of your trip.
One tip I would give you is to take a good GPS so you can always find your way back to your hotel. A couple of times we were all well back and some stragglers didn't get back till we were properly "settled"
Bon voyage mon ami!