If you have time and want to discover the area, you can enjoy those 100km with scenic roads and it will take you 2h30 (if you do not stop which will be a shame).
Leave Annecy, go to Veyrier du Lac, then turn on the left, follow the sign Thônes leaving the lake on your right. After a few turns stop quickly at the panoramic parking on your right, from there you have a lovely view on Château Menthon St Bernard.
Then follow the sign to Thônes, before arriving in the city, you will have the Morettes cemetery (a memorial for the resistance during Wolrd War II, 500 resistants were hiding in the Glières, mountain above on the left, 129 jumped from the cliff declaring to the Germans "Live free or die").
Thônes is the hometown of the famous Reblochon cheese, so if you wish to buy one this is the place (you can ask the shop to put in a vaccum bag to avoid the smell). You can also have a little walk in Thônes. You can park at the Gare routière (turn left at the round about and follow the sign La Clusaz and on the right at the traffic light).
Then continue up to La Clusaz ski resort which is really busy during winter but also nice during the summer. It can be a nice place for a coffee break and a little walk.
Follow the sign, route des Aravis to reach the Col des Aravis (be careful during winter the col is closed because of the snow). It is famous with the Tour de France and a lot of cyclists enjoy going up to 1486 meters.
You will continue to Flumet (Savoie) then head to Megève, famous ski resort as the family Rothschild decided to spend some time there in 1910.
Drive the road to Sallanches, Combloux, St Gervais les Bains (famous for spa and thermal treatments), Le Fayet, Passy then finally reach Chamonix.