Spin Semiconductor

Is this a problem? Presumably, it's best practice to tie an unused pot pin to +v or ground or MID, but if there was a situation where that wasn't possible, is it bad to leave a pot pin connected to nothing?

While it should be ok, it is always best to tie them off. Can't think of how tying them to GND wouldn't be possible as there is a GND next to POT0 so should be able to tie right across all three POT pins to GND.

Well, it has to do with switching jacks. I'm trying to fit the board in a really tight space and getting a stereo switching jack (6 contacts) in there is nearly impossible.

I need the pot input to be usable with an expression pedal, but when the exp. pedal is not inserted into the jack, the pot input would be floating unless I used a switching jack to connect it somewhere when nothing's in the jack.

In that case, I would try adding a high value resistor (i.e. 1M) from the POT pin to gnd so when not driven it will be pulled down.