A desert of some type would also work well if the potluck is on the 2nd or 3rd day of the trip. This you could make the evening before you depart and it would still be fresh. Only problem would be storing it until needed, but at least it wouldn't need refrigerator.
My DW usually bakes chocolate or sugar cookies for any potluck event we attend. We were thinking about changing it feeling repetitive, until we noticed they were always the first thing cleaned out and folks were asking for her recipe or complaining they had tried to use her recipe and they just didn't taste as good.