OK, I think this post was probably intended for me.
Heppenheim is on the edge of the Odenwald, but it's a great little town. Fachwerk it has, plenty of it, but the actual Fachwerkstraße lies a little to the east... goes right through the heart of the Odenwald. The emphasis of the Bergstraße is mostly wine.
Let's see, hikes near Heppenheim that aren't too rough on the knees... It depends on how much uphill you can tolerate. Here's a few idea. Drive up to the castle (Starkenburg- the narrow road that leads up to it is a little tough to find. Blink and you'll miss it). Park your car in the lot, and you'll see the trail map. Walk in the opposite direction of the castle and you'll eventually hit the woods. Nothing too steep, but it does ascend very gradually. Some of the hiking loops go through some gorgeous old-growth forest, but the trails get a little steep. If you keep walking straight and avoid any of the side-trails, it only very gradually ascends.
Option two, but a little steeper. Park by the Friedhof, and follow the trail up through the vineyards. You'll hit the woods at the top, and once you hit the trees, the inclines are fairly mild.
Option three. Drive up to the little subvillage of Juhöhe. Right before you reach the village, there's a parking area on your left, with some picnic tables, a map and the trail head. There's a nice hour-long hiking loop that starts from here. Nothing terribly steep, although there is a sustained uphill portion 3/4 of the way through.
If you want to dive deeper into the Odenwald, check out Lindenfels, Michelstadt and Eberbach. The scenery of the drive itself will make the visits worthwhile.
All the restaurants on the Markt in Heppenheim are pretty good. Goldener Engel included.
Too bad I don't live in Hüttenfeld anymore, I'd meet you in Heppenheim.
BTW... Ludwigshafen is pretty ugly, Speyer is a world apart. One of the best preserved cities in the region.