I was in Paris on Christmas Day and just about everything was open - huge crowds milling about - the French clelbrate Xmas on Xmas Eve and Christmas is just another Sunday so loads of restaurants should be open - even some museums were open!

This may be true of Catholic countries or just France I am not sure.

I suspect many restaurants will be reservation only, even though in France and Austria (and probably the Czech Republic too) Christmas is celebrated at home on Christmas Eve.
People still like to go out and enjoy a celebratory meal together.

In The Netherlands the main Amsterdam museums are open, as are restaurants, but certainly most will require a reservation. Some Chinese/Indonesian and other ethnic places don't, but certainly in my small town even they do.
For Belgium I imagine Vlaanderen is similar to the Netherlands, but I'm not sure, and I have no idea about Wallonia I'm afraid.

We couldn't find any restaurants open in Vienna for Christmas lunch (we grabbed a sandwich at a pub or whatever: there were a number of modest eateries open). No-one on the streets but us worried much: they'd all had their big meal before midnight Mass.

We had a reasonable supper at our hotel (the K&K), but even they had pretty limited service and choice. Their Christmas Eve menu was robust, substantial and challenging both to the digestion and the wallet.

But both suppers were fine. Once we'd got our heads round the fact that they just do Christmas eating differently, the whole period was memorable. Nowhere in Western Europe outside SE England does liturgical singing as well as Vienna - and from that point of view, it's the best place on the continent to spend Christmas.

Stay at a big hotel for Christmas and you can check with them. Either that or rent an apt.

We were in Paris on Christmas Day 2000. It was difficult to find a place that was open, not limited to costly reservation only holiday meals, and had good affordable meals. Eventually had a good meal in a bistro in the Marais.

You've got plenty of time to figure out where you'll be on Christmas Day, do some research, and make a reservation.

Thanks for the helpful replies. Asking an occasional question on Fodors is part of my research.