[bobert]

Make sure to affix the Swiss vignette to the windshield (vs just keeping it in hand), as failure to do so can result in a hefty fine.
Get some Swiss francs (coins for public restrooms) since many places there don't accept Euros.
Hit Klausen pass if you're entering Switzerland from the east. Also hit Grimsel and Susten right after Furka.
Use the car's speed limit display and stick to it on Swiss roads as they can be quite stringent about speed limits there.
Use gas stations with an open convenience store so you can pay inside with your "swipe & sign" US credit card (vs the "swipe & pin #" credit cards that have taken over Europe).