I also always carry my camera. I alsmost never buy film, until we get to orlando. I pick it up at our grocery stop.
We use Snapfish.com for our developing. E-mail them ahead of time to get plenty of envelopes for mailing, and mail our film as we use it from our resort. Sometimes the pictures are waiting for us when we get home. They post the pictures on-line within a few days. Works great.
This way, it saves packing space, and eliminates the "will my film get ruined" ????