We've stayed in Amboise twice and really like the town. It's pretty much in the middle of the Loire so we chose it for the convenience of visiting many chateaux. Amboise is on the river, is charming and very walkable... it has many restaurants, fun shops, and Leonardo di Vinci's last home, which I recommend visiting.
Blois (no "e" and the "s" is silent) is a very nice little city, also on the river, with a wonderful chateau... but I wouldn't choose to stay there, only because I like smaller towns. Same reason why we didn't choose Tours, it's a city and not as well located for our purposes as Amboise.
We've stayed in two hotels in Amboise... Hotel Belle Vue which I do not recommend (dirty, moldly, unfriendly owner - may have improved since we were there though) and Hotel Manoir les Minimes which I highly recommend but it's expensive. TripAdvisor is a good source for finding hotels.
Some chateaux have a light and sound show at night... Google for info on that.