Depends on where I'm going and what I plan to do.
For instance, I'm taking a trip from PA to FL in the near future.No requirement to conceal in PA but FL is strict about concealing and I'll likely be wearing light weight cloths so I'll take something small like my LCP or j-frame. A few months ago we went to upstate PA for a week, I took a 9mm Glock because it was PA and a little cooler.
I'll take a couple extra mags (or speed loaders) but I have yet to realize the need to take more than one firearm, quite the opposite actually, I don't want extra guns laying around or packed away while traveling, one gun under my control all of the time. If my wife chooses to carry, same thing applies.