I followed the link Enerson gave, and on that page there is a link to "A Guide to Using Travelers Cheques" (sic).In this 2-page Guide there is a list of countries, which does not list Austria, but it does say "EUROZONE COUNTRIES: Travelers Cheques acceptance in the Eurozone is very limited away from airport locations. This document indicates partners who, at the time of publishing, were known to be encashing Travelers Cheques for non-account holders. You are strongly advised to use the TC Locator americanexpress.com/useTC to confirm the latest position".
They are selling the things, and even they admit they are difficult to cash.
The "TC Locator " on the web page does list the following locations in Vienna whch allegedly accept them:
1. Interchange Austria GmbH Stephansplatz 9 Vienna, A-1010
2. ChangeGroup Singerstrasse 1a Vienna, 1010
3. Erste Bank WohnbauCenter Wien, Brandstätte 7--9 Wien, 1010
4. ChangeGroup c/o Laks, Kärntnerstrasse 16 Vienna, 1010
5. Erste Bank Graben branch, Graben 21 Wien, 1010
6. Erste Bank Kärntner Straße branch, Kärntner Straße 45 Wien, 1010
7. ChangeGroup c/o Sacher Hotel, Kärntnerstrasse 38 Vienna, 1010
8. Erste Bank Wien-Mitte branch, Landstraßer Hauptstrasse 1b Wien, 1030
9. Erste Bank Ringturm branch, Schottenring 30 Wien, 1010
10. Erste Bank wohn²Center Wien branch, Praterstraße 38 Wien, 1020