Best place to be on Christmas Day in Europe

Please define best. What are you looking for? Christmas traditions vary between countries and regions but can broadly be grouped into three main "branches", the catholic, the protestant and the orthodox. For Christmas day on 25/12 you should probably avoid orthodox countries as some of them celebrate Christmas in january.

Any reason for including Denmark in the list? I have to say it is an odd choice (but not necessary a bad choice). And note that Christmas is celebrated on Christmas eve in the Nordics. I'm not too familiar with Austrian and Swiss christmas traditions though. But the Germans do Christmas well, as do many other countries. However, in many parts of Europe the countries more or less shut down over Christmas and you might struggle to find an open restaurant or public transport.

If you're looking for a white Christmas, you should probably head north or around the alps.

You know, there's a "Rick Steves Christmas in Europe" TV episode special they made a few years back. I'm sure it's widely available (maybe even via a link here?), might give you some ideas and help you narrow down your search.

Sorry I wasn't clear. Specifically re: best on Christmas Day, I'm trying to avoid places where I would experience what you mention about those that shut down: not being able to find places to eat or transportation.

Denmark is on the list because my husband is interested in going, and people rave about the Tivoli Gardens though honestly I'm not sure that is my sort of thing.

Overall, we are looking for places that would have pretty decorations, potentially some markets, and overall a Christmassy feel.

Francie - Nuremberg Germany may interest you, it has a huge Christmas holiday market and Christmas there is a magical experience. You will definitely experience that Christmassy feeling you seek over there.

Nuremberg would be a bad call because Christmas markets close before Christmas, on the 23rd or 24th typically. Only a handful of markets in Germany are open after Christmas, the one that comes to mind is Speyer, near Mannheim.

Berlin's Christmas markets start on 11/25 until 12/31.

Thanks for the thoughts on Nuremberg. We are planning to arrive in Europe ~12/20 because I know some markets close before Christmas.

We've seen the Christmas markets in Vienna, Salzburg and Innsbruck Austria. Innsbruck's is smaller, more compact, but very nice and right in the heart of the central shopping area. You'd certainly see snowy mountains! Innsbruck is also a very walkable city. I'm not certain about Christmas Eve and Christmas day closures, though for any of these. Salzburg was our favorite for several reasons. One we already love Salzburg, . Two, it is larger, but all central and very walkable. When we were there, they had an ice skating rink set up nearby. Salzburg is also very walkable. Vienna is a large city with several markets and more 'typical' street/shop deocrations. They have the tram system also.

Denmark is on the list because my husband is interested in going, and
people rave about the Tivoli Gardens though honestly I'm not sure that
is my sort of thing.

Not a bad idea, Tivoli is supposed to be nice, but I haven't been there before Christmas myself. The weather tend to pretty bad close to Christmas though.

Overall, we are looking for places that would have pretty decorations,
potentially some markets, and overall a Christmassy feel.

Most people probably have their own definition of Christmassy feel so it might be hard to recommend anything. But it has become more common, at least here in Sweden, for hotels to offer Christmas packages with everything included. Did a quick google search and found Hotel Lappland in Lycksele: https://www.hotelllappland.se/paket/41795.julpaketet.html Or Saxnäsgården in the small Village Saxnäs in southern Lapland: https://saxnas.se/jul-i-saxnas/
Or if you prefer the coast instead of the mountains, Hotell Havsbaden in Grisslehamn: https://www.hotellhavsbaden.se/jul

Also, it's normal for Christmas markets to close before the 24th. They originated as (and still are) a place to buy things you need for Christmas, so there is little reason to keep them open after Christmas.

Most Christmas markets close on the 22nd or 23rd, so that the workers can all be home by the 24th, which is when Christmas is celebrated in Germany as well as many other countries. The 25th is a holiday, but it is not the main celebration. The 26th is a holiday too in Germany. Be prepared for almost a complete shut-down of the country on the 24th after 1300-1400. On the 25th and 26th, restaurants will be busy and a lot of tourist attractions will be open again, but check their websites. Christmas Eve is a family affair, with a lot of church services, nativity plays with kids. In Frankfurt, for example, they have the Pealing of the Bells on the 24th which is unique, but then everyone goes home, eats their nice dinner and opens their gifts.

Look for cities that have longer markets, like Berlin or Strasbourg. Berlin is going to have more going on than being in a small town. If you want a snowy type of Christmas like you see in Ricks' videos, you need to make reservations sooner rather than later at a ski resort type place in Austria or Switzerland.