First time in Vienna

Last September we really enjoyed a day trip from Vienna to Melk to visit the abbey. OEBB has a kombiticket (see: https://kombitickets.railtours.at/wachau-ticket/austria/wachau/wachau-ticket.html) which was very convenient, but the RS guidebook touts a slightly less expensive way to do the same thing. Have a great trip.

check out this previous thread for the best Coffeehouses:
https://community.ricksteves.com/travel-forum/austria/coffee-houses-in-vienna

I enjoy seeing the beautiful objets d'art of the imperial court and really enjoyed the Imperial Silver (and porcelain and china, etc.) Collection at the Hofburg Palace as well as the objects in the Kunsthistorisches Museum.

It will be winter and likely very cold. Not exactly day trip weather.

Obvious activity for December - Advent Markets. Visit one or two every day. Karlsplatz, Schonbrunn, Altes AKH, Rathaus, Spittelberg, Belvedere, Freyung are all great market choices.

Otherwise, plan for indoor activities, like museums, cafes and palaces.

Emily's comments about the December weather in Vienna should be carefully noted by anyone planning a trip.

For a short overview of the main sights:

https://www.wien.info/en/recommendations/vienna-in-three-days
https://www.suitcaseandwanderlust.com/3-days-in-vienna-itinerary/
https://www.placesofjuma.com/3-days-in-vienna-travel-itinerary/
https://www.visitthecity.de/en/wien/

We spent Christmas week in Vienna. Weather wasn't really a problem, but you must dress right and keep your feet dry.

To stay warm, focus on indoor sights: 1] Schoenbrunn long tour & Carriage Museum; 2] Hoffburg (essential: State Library); 3] Many, many museums. There is a tram (sort of indoors) that circles the Ringstrasse.

Do not miss Melk. I've been there 18 times. Train & bus to Melk are very slow. Take a local tour operator from Vienna. Or rent a car at/near the Wien Heiligenstadt Bahnhof which right at the start of the scenic road to Melk (through the Wachau Valley).

Since you will be visiting Vienna in December I would skip any trips outside city. Also Schonbrunn and Belvedere with its gardens are not so attractive during winter as they are from, say, April to November. So maybe december is ideal to visit Hofburg and some museum, my reccomendation would be KHM Kunsthistorisches museum (Museum of Art History). It is huge and one of the best in the world. https://www.youtube.com/watch?v=znG9rEiF2o8

For cafes, the most popular is cafe Central, however it is too touristy now (there was a 10 meter queue last time I was there). The same goes for cafe Sacher and Demel (nice but too crowded). I would reccomment cafe Sperl, cafe Gerstner (very nice interior) and cafe Landtmann. Reaturants: you wont miss with Plachutta there are a few in the city but central is one at Wollzeile near Stephansdom. Try vienerschnitzel here since it is not as good ewrywhere. Their trademark is Taffelspitz-boiled beef. For something cheaper, Nordsee fish restaurant chain offers good quality and there are a few around the city.

Train & bus to Melk are very slow.

REX-Train (Regional Express) to Melk from Wien Westbahnhof is one hour. You can't make it with a car in that time.