A weekend without a hurry
Two days, done properly, with nothing on the schedule.
A weekend in the mountains fails in a predictable way: you arrive having planned six things, and because you planned six things you do one of them properly and rush the rest. The fix is not more time. It is fewer plans.
Day one: arrive properly
The first day should cost you nothing. Walk into the village, do the waterfall — five minutes, easy, all seasons — and then let the afternoon be unscheduled. This is the day you find out what the place smells like at different hours, which is more useful planning than anything you could have written down.
The first afternoon is not for exploring. It is for finding out what the place is like when you are not looking for anything.
Day two: one proper excursion
Choose one. Serolsar Lake if you want the widest views and most of the day; the forest trails if you want a half-day and no driving. Both are on the Explore page with honest distances. Whatever you pick, start early enough to finish before the light turns hard, and resist adding a second thing on the way back.
Leaving on time
The most underrated part of a good weekend is the departure. Leave with enough margin that the drive home is not a race, because the drive home is the part of the trip people arrive home from still thinking about. Three hours of road is a fine way to finish a weekend. Two and a half hours in a panic is not.
Do all that and you will have walked a great deal less than the ambitious version and remembered considerably more of it.