Vienna Day Trip Help

There are direct and fairly frequent train services from Krems to Vienna, there's no need to go back to Melk.

On Salzburg, I think you could do it as a one night trip and get something out of it, but do you really want to spend all that travel time for very little reward? I'd combine Salzburg with other locations on another trip.

It is also worth noting that you will be in Vienna on a major long holiday weekend (Pentecost). Monday is a federal holiday and many people will be going away for the weekend. Shops will be closed on Monday, but restaurants and museums will be open. Transport will run on a holiday schedule and you will want to reserve seats on trains for any longer journey.

The Wachau Valley will be stunning in May, really the best time of year. I also think that your itinerary is very city heavy, so it will be nice for you to be in smaller villages - even if for a day.

I've been to the Wachau many times. Rick's book is ok for details, but I would look elsewhere for additional resources. As noted above, there is no reason to backtrack to Melk. I also think that Melk and Krems are the least interesting parts of the Wachau. I prefer the small villages and apricot orchards and wineries in between. Nextbike has locations in all the Wachau villages and you can drop off/pick up in different locations. I would suggest taking the train from Vienna to Melk and picking up your bike. Have lunch in Weissenkirchen at someplace like Restaurant Heinzle or Weingut Hermenegild Mang. Then head to Durnstein where you can hike up to the castle ruin and have an apricot dumpling on the terrace of the Richard Lionheart hotel. Then head to the Krems train station where you can ditch the bikes and get the train back to Vienna.

Some specific winery recommendations (there are 500 in the area, but these are some of the best):
WEINGUT KNOLL - in Unterloiben, famous wines and an excellent Restaurant "Loibnerhof"
DOMÄNE WACHAU - in Dürnstein; the only cooperative in the valley. Great selection of good wines.
WEINGUT SCHMIDL - Organic wines-good.
FX PICHLER - in Dürnsein:the star of winemakers. Very modern and sterile-but good wines, pricey though.
WEINGUT PRAGER - in Weissenkirchen; Famous Winery, great wines.
WEINGUT JOSEF JAMEK - in Joching, the godfather of winemaking in the valley- good wines and good restaurant
WEINGUT HOLZAPFEL - in Joching, wines not so great, but the court with the Restaurant on a sunny day fantastic.
RUDI PICHLER---in Wösendorf, a new star, very nice wines, expensive.
WEINGUT HIRTZBERGER - in Spitz, the new Number One of winemakers.
WEINGUT LAGLER - in Spitz, Nice wines, great views, nice hotel.

I will just comment on the Budapest part.

If you have to do the Eger trip put it in the middle of the stay and not at the end so you can wind down before heading home. If you are doing the trip for the wine, you need two nights there.

If its just wine that you are interested in, then a day trip to Etyek might do the trick for you and leave you sufficient time to see Budapest.

Emily, do you think doing the Melk - Krems trip would be good for the Monday after Pentecost or should we plan to do that on another day? I just don't know if things will be open for us. Is the Abbey open 365 days? The website doesn't note any closures

Melk Abbey is open daily.

Wachau is a touristic area, so expect everything open even at Pentecost. Only the trains will run on holiday schedule.

This is the bike company which has a pick-up/drop points both in Melk (4 locations) and Krems (6 locations):
https://www.nextbike.at/en/wachau/locations/
Read the details thoroughly to get acquainted with the procedures and rules.