Padded cycling shorts essential - and maybe consider gel saddle pads too. Cycling gloves are unnecessary.
Take mosquito repellent plug-in devices
Don't bother with the son-et-lumiere in Amboise on your first night, espcially if you don't speak fluent French or got up early to get there!
Book restaurants ahead of time for the days where you are not half-board, particularly in Chaumont, as there isn't much choice and everywhere was full. Even booking something at lunchtime would help.
Detailed itinerary arrived only two days before the trip - more time to prepare would have been helpful
The Relais D'Artemis restaurant in Bracieux was closed when the notes said it was open (and open when the notes said shut) and was very disappointing - the one poor value for money meal we had. Actually it would have been poor even it it had cost the same as the others.
On the other hand the restaurant in the square opposite the Hotel Du Cygne - The Au Fil du Temps - was much better (and cheaper) and a really nice experience. We suggest you recommend that one instead.
The route notes became unhelpfully brief at some points of the trip - particularly the last afternoon - and we went the wrong way as a result.
It could be more clear where meals are included and not included in the trip notes.
The bike shop was closed at both ends of our trip. It would have been useful to know this in advance so we didn't have to make another return trip across Amboise to return the bikes when all along they were going to be picked up from the hotel. We also missed out on any adjustment/instruction on the bikes before we set off and didn't have a full set of panniers/bungees until another traveller complained to the local rep. Brackets to hold water bottles on the bikes would have been useful. Otherwise, the bikes were in very good condition.
It would have been useful to have a map with the official bike routes marked on them, so it was clear when were were supposed to be following them, or not.
It would be even more useful to have an iPhone app with the routes and points of interest overlaid on the map. We had no idea what distance we had covered until we came upon a town or other landmark.
On the return leg, the train booking left us with an unnecessary change and 1:30 hour wait in Blois. We didn't get this schedule until the tickets arrived two days before we left. We were then told we would have to pay to change the tickets to catch the direct train, but when we tried to do this, the ticket office said the tickets were flexible and we didn't need to. It would also have been useful to have been told that we had to validate the tickets before getting on the train.
It would have been useful to include information on the chateau card (offering discount for visiting lots of chateaux) as we only found out about it after paying for most of them individually.
The price for the horse spectacular at Chambord was a lot higher than was said in the route guide.
Overall we ended up spending a lot more money than we thought we would need to.