Loire Valley recommendations

Have you read Rick Steves’ book on France yet? If not you need to check it out. It has answers to a lot of your questions. That might help the forum answer your specific questions.

If you don’t have a guide book yet you can start here
https://www.ricksteves.com/europe/france/loire

I would recommend doing a chateau tour, which enables you to see quite a few in one day. We visited Chennonceau on our own, which is easy to do as it has its own train station- this is one you have probably seen in photos of the Loire Valley with the long gallery that stretches across the river. On a day trip from Tours with a tour company, we visited Azay-le-Rideau, Villandry (just the gardens, which is the most spectacular part), Cheverny (known for beautiful furniture/interiors and very well trained pack of hunting hounds), and Chambord (huge and very impressive chateau designed by da Vinci). Since you are staying in Amboise you can also visit that chateau, and see da Vinci's bedroom- the most exciting part tho is the replicas of his inventions in the garden. The Loire Valley is also a well known spot for hot air ballooning if that is of interest.

Lots of bike routes (and maps) are available. Chenonceau is a great day trip by bike from Amboise. Ditto for Chaumont. And there is quite a story linking the two chateaux, Henri II, Diane de Poitiers and Catherine de Medici. Bedfellows make for strange politics. Those two chateaux were my favorites of eight that we visited while cycling from Blois to Saumur, two years ago. The gardens at Chaumont are delightful.

Of course, there are two chateaux right in Amboise: the Royal Chateau Amboise and Château du Clos Lucé. Personally, I found Clos Luce, with models of Leonardo da Vinci’s designs in the gardens and with other exhibits of his final years, to be more interesting than the Royal Chateau.

For biking ideas, perhaps https://www.freewheelingfrance.com/ can get you started under their bike hire tab. Googling “rental bikes Tours France” will get you shops in Tours, which is not far from Amboise, and more to the point “rental bikes Amboise France” yields results.

Bonnes Vacances

You will be there 3 full days. There are 3-4 Chateau that are world class tourist sites that are 3 star attractions in every guide book. Should we assume you are up to speed on those and want off the beaten path ideas or would you like us to summarize the regions greatest hits? With 2 days for chateau and 1 day for bike riding you would have to make some cuts if you go off the beaten path.

I really liked the Chateau right there in the center of Amboise. Not as expansive as the others, but interesting enough, nice view of the river, and worth seeing while you're there. And the grave of DaVinci to boot.