In reply to StefanB:
The hike to Seealpsee if very easy, you can park at Wasserauen-Ebenalp, should be on your route to Liechtenstein.
You can take the normal road up to the lake and hike around the lake. At the car park there is however another route on the left going uphil (first through the grassland and than in the forest), which is much nicer.
https://www.komoot.de/smarttour/637361
If you just want to go for the view, you could take the cable cart up to Santis, but will be pricy.
Walensee is really beautiful, I go there alsmost every other weekend (multiple climbing locations nearby). In Murgtal near Walensee you can boulder, it is just of the highway. Other options in the neighbourhood are Pizol, Flumserberg for a winterhike.
There is so much to do, so you should be able to have a great time, enjoy!