To be honest, as many days as you can get. In Chamonix, you might spend weeks and yet not see everything. However, even if you just had a few days, a vacation to Chamonix in the summer might be worthwhile.
Depending on the time of year, during the busy season, access to the most popular activities needs pre-booking. It might take longer to be in town.
A whole week would be ideal for those who aren’t gifted with infinite vacation time. You could visit the most remarkable sights in a week, go on some of the best day treks, eat delicious alpine foods, and yet have time to unwind.
The activities may be packed into even 4 or 5 days, though.
If you are looking to relax and take in the village atmosphere, a stay of at least a week is recommended. This will give you enough time to explore the boutiques and restaurants, as well as the local bars and cafes.
No matter how long you decide to stay in Chamonix, you are sure to have a memorable experience. Whether you are looking for adventure in the outdoors or want to take in the village atmosphere, Chamonix is a great place to spend a few days or even a few weeks