Air B&B can be hit & miss. My parents weren’t at all impressed with their accommodation last year for the amount they paid.
This year they stayed in Hotel Le Louvre in the centre of town, even though they thought the prices were too good to be true when booking (I gave them a list of hotels and they checked prices for all of them, and thought Le Louvre’s price was per-person at first, not for 3 including my sister). Perfectly adequate room, fair breakfast, nice staff. Ask about bike storage before booking though.
Stay in Chamonix centre if you care at all about nightlife. Everywhere worth riding is a ride/drive/bus/train to access anyway but if staying in town at least you get an OK off-road route most of the way back to town from the top end of the valley and you’re central between Le Tour and Les Houches.