Would miss it
I'm planning a vacation to get away for a week during the winter. On one hand I would love to be able to leave the iPhone behind and get away from email, text messages, and having people call me. On the other hand it will be nice to have the Internet to check out restuarants, find interesting things to do, and navigation for getting around. The iPhone is the best portable tool for that purpose. It's much more convenient than fooling with maps and tourist brochures.
The problem is I will be tempted to play with the other stuff.