Swappa will require the device to be paid off and ready for activation (i.e. clean ESN) before listing. Which you really should do before selling it anywhere. Or at the very least, make sure you note what your plan is, as the buyer won't be able to activate the tablet until you pay it off and remove it from your account. Verizon is rather particular about that.
If that's the case, you may want to coordinate something locally through Craiglist and meet a Verizon store, maybe?
Assuming you can't pay it off first...
Either way, good luck.