We have to be in Frankfurt for business on the first Tuesday in January. In the past we have flown on Thursday night and gone to Koln one year, and Heidelberg another, for an easy close by stay for the weekend.
I understand that January is not the best time of year to be a tourist in Germany. . That being said we like to explore if we can.
We will be there the first weekend in January. Is that Sunday a holiday?
any thoughts on
Wurzberg
Rothenburg
or we are open to suggestions.
Or maybe just fly to Frankfurt Sunday night

January 1st 2023 is a Sunday. Sunday is already for all intents and purposes a holiday in Germany (stores are closed except grocery stores at major train stations; transportation schedules are reduced to Sunday/holiday levels). Or when you say "the first weekend in January" are you referring to the following weekend (Jan 6th/7th)?

yes jan 6/7

January 6th (Epiphany; the 12th day of Christmas) is a public holiday in Spain, but not in Germany. Germany ends its holiday festivities on New Years Day, January 1st (in many countries if the holiday falls on a Sunday as January 1st 2023 does, then workers often get the Monday off - - this has not been the case in Germany, but there is currently a movement to change that).

So the 6th and 7th will be like any other Saturday (limited hours in small towns) and Sunday (most things shut down except museums) - - except that individual businesses/museums etc. may choose to close if they need to because of the ongoing problems with staffing shortages - - and/or whatever viruses may be happening in New Year 2023!

Wait, is January 6 not a holiday in some regional parts of Germany? I thought that it is observed in the south still, but not in big cities. Just watch that, there may be some hiccups around Jan 6 still. Bavaria, Baden-Württemberg, Saxony. It's the Heilige Drei Könige.

As for your weekend away, Würzburg is good (close at hand), but Rothenburg odT too far for my liking. Have you not been to the middle Rhine gorge, or Mainz and Wiesbaden? Mainz in particular has a lot to do and everyone must do a Rhine cruise. Or just stay in Frankfurt and take day trips out to destinations in Hessen: Limburg an der Lahn, Idstein, Marburg and/or Michelstadt (all pretty, but not much to occupy you). Texas Bookworm (or is that Texasbookworm) has the gold standard of short trips out from Frankfurt, look for her name in the forums to find her trip reports.

Lavandula

Brilliant insight, Lavandula! That's something that living up in Hamburg I would completely miss. It is still an official Feiertag in Bavaria, Sachsen-Anhalt, and Baden-Wuerttemberg. So if you head down to Heidelberg or Wuerzburg you might have some closings.

Strasbourg?
How are you planning on getting around?

Yes we had issues with closings in Heidelberg on Sunday a few years ago. We will do trains. Going to Mainz and Weisbaden seem like a good idea. MAybe do day trips and not move around. I think we could even do a day trip to Wurzburg.
Thanks for your info.

Luneburg,

It's nice to base in Mainz. Plenty of decent places to stay right by the train station, where it is only 20 minutes by direct train to Frankfurt airport.