Brussels

There are direct flights to Lisbon and Paris

Vienna is amazing. You can see a lot in a long weekend, though you may want to go back!

I would pick based on getting a direct flight -ideally one that leaves late. Flights to Europe that leave at 6pm are tough for me because I have trouble falling asleep right away. I'd much rather leave at 10pm.

Direct flights limit you. How about Vienna or Copenhagen?

No one has said Paris, but you can see plenty in a weekend.

Brussels or Bruges

I think you want a city that has a lot of sights right in the city center and has a major airport close by, so that you don't lose time to transit.

A second vote for Amsterdam, which fits the bill. Rome has a ton of sights in the city center, but the flight is longer.Nice might also work.

I was thinking Venice

Thanks!
We also did Ireland for our honeymoon, and I have a childhood friend in Amsterdam that I'd feel obligated to "visit."

Krakow is definitely on my bucketlist! I'm hoping to find direct flights from IAD

Amsterdam is mostly walkable, definitely doable in 3 days. I did Dublin in December and Ireland is full of cozy pubs with warm fires.

Venice
Salzburg
Edinburgh
Lisbon

for the weather, I'd go to Venice or Lisbon

3 days in any city is great. You may not see everything, but I'd rather see some of a city than never see any of it.

Vienna
Krakow
Barcelona
Budapest

You can explore pretty much any city on a weekend. You just get on the plane when your time is up.

Arrive early Saturday morning (Red eye from Friday night out of Dulles) and leave on Tuesday.

Any European cities that would be "worth it" for such a short period?
We've already done London, Prague, Florence, and Munich...would like something different. it would be late March, if it makes a difference. Thank you!