This was mostly a business trip: here's the plan. But there was a lot of time for fun visits (but not quite enough to go to the Netherlands and get the bike.)
Saturday, I changed to a more reasonable hotel near the train station. I wasn't feeling well, so I just took a boat trip down to Necarsteinach, though I did do a quick tour (1 hour) of the the Philosophenweg first, and relaxed in the evening at the nice restaurant near Bismarkplatz. Sunday, I went to see the transportation museum in Simsheim. Monday was another work day at SAP and then Tuesday I traveled to Berlin, from where I was leaving the next day to Tenerife.