I'm only using my Touch to control the music and film playback at home, which means I won't need the 32GB one - but it's probably a good one to have if you plan to travel with the Touch. Mine spends its time being charged in my AudioPro, and I can also control it remotely while it's in that dock. If I didn't have a music centre I would probably want as much music on it as possible, though.
When I want to control my music centre the Touch is ready with a full charge and gives me two-way access to hundreds of GBs worth of lossless music.