I'm doing a trip from Vienna to Salzburg just after the beginning of the new year, probably 2-3 January. I'd like to stay for a day and night in Salzburg, but would also like to do another day and night somewhere smaller and more provincial. Is Wachau more than just a place for skiers? Or could I make my own fun as a non-skier? Same question for Pongau.
I don't know where you got it from, but the Wachau is definitely not a ski region. So, yes it is fine for non-skiers. By definition, so to say. The Wachau a quite picturesque region. It has some interesting historical monuments. The Wachau is also famous for its wine. An interesting way to explore the place and enjoy the landscape is by cycling. Have a look at the Donauradweg.
The Pongau is a ski destination. But as anywhere else in the Alps there are plenty of other things to do. For instance Bad Gastein is a thermal resort. A nice place to relax not only for skiing.
If you are travelling through Wachau, the ruins in Duernstein and Loiben are remarkable, Duernstein having a connection to the myth of Blondel the singer. Both venues offer breath taking views of the Danube. And of course the local cuisine is a treat.