I don't know Bellheim, but I'm very familiar with the region.
Some nearby attractions:
Speyer, with it's huge Romanesque cathedral and pleasent Altstadt.
The Schloss and gardens at Schwetzingen.
Heidelberg and the scenic Neckar river valley, especially Hirschhorn, Dilsberg and Bad Wimpfen.
The Deustche Weinstraße, although there probably isn't much to see or do in February. If the weather is particularly cold, though, the saunas and thermal baths of Bad Dürkheim might beckon.
I've only driven by, but there appears to be two interesting castles at Annweiler am Trifels.
Karlsruhe is somewhat of a modern city, but it too has a very nice Schloss and attached park.
Mannheim is the largest city in the region, but skippable, especially in February. It has one of the most beautiful urban parks in the Europe (Luisenpark), but there won't be much to see in February.
The Rhine by Bellheim could just as well be any river anywhere in the world, but you're within daytrip distance of the scenic Mittelrhein. On the left bank of the river (your side), the interesting scenery starts at around Bingen and runs north to Bonn.
