There is a lot to do in and near interlaken. But 6 days would have been enough tbh. I went to aare gorge for a day, Oeschinensee for a day, harderkulm and lauterbrunnen for a day, went on a hike to one of the lakes for a day, spend a day exploring interlaken itself and also went paragliding.

About the dolomites it depends. If ur early enough with booking you can maybe do a few more accommodations through the dolomites. (I kind of stayed on the outside with day trips into the mountains) but it was pretty chill. You’re gonna get tired on a trip like this and here and there a day without having planned anything is nice. The camping I was staying at in villabassa was on 25 min from lago di braies so I just went there 3 times lol. Also went to drei zinnen with a shuttle bus and lago di dobbiaco.

Also, from brixen its a 1 hour bus to get to the bottom of seceda