If I vote 3rd party, it'd be for Johnson not writing in a candidate whose not actually running. The main practical reason I'd vote third party would be as a protest vote in hopes of the 3rd party candidate garnering enough of a percent of the popular vote to potentially send a message to the Republicans. As long of a shot that may be, writing in Paul would not even have the chance of causing that.

With that said, especially being in a swing state, unless Romney does something between now and the electoin that causes me to simply be unable to in good conscious vote for him, I'll likely not be casting a 3rd party vote.