Koblenz

Hotel standarhs in Germany are very high. Recommendations aren't worth much because nearly everybody loves wherever they stay If you must have a recommendation, get a Michelin Red Guide to Germany or check Fodor's web site. After a few weeks of travel in Germany, we stopped looking up recommendation & went by looks and price.

The old town isn't much, but the rest is pretty bleak.

I'm not exactly sure meets your "pension" definition but we stayed at Hotel Trierer Hof and thought it was fine for 2 nights before/after a 1/2 day Rhine cruise from Bingen. Not fancy but clean and breakfast included in the tariff. No A.C.

https://triererhof.de/?lang=en

(From a previous post, I see you'll be in Koblenz for a wedding.)

Don't forget to visit the Konisbacher Brewery beer garden south of Koblenz. They have a small beer garden overlooking the Rhine River, and it's a great place to spend a couple of hours.