For a simple trip to another country, I could suggest Budapest. It's a 3-hour trip from Vienna, on a very comfortable train. Accommodation & food both are less expensive than in Austria, and the city is easy to get around, on foot or by public transportation.

There are a number of small, reasonably-priced hotels & pensions, most of them on the Buda side of the river. A couple I can recommend are the Hotel Papillon http://www.ohb.hu/papillon/index.en.html#rates

and a newer hotel, the Fabius Panzio (www.fabiushotel.hu)

Julie in Seattle