-make sure your driver’s license isn’t expired (happened to us!) and maybe have a backup form of ID too
-pick your time of day based on the best light if you plan to do some photos outdoors before/after or arrange for the photographer to shoot during the pretty light!
-I brought my dress in a folding suitbag and was nervous about it but didn’t have any trouble, just double check before you fly and make sure to say it’s your wedding dress a lot so they understand how important it is :) (if you’re flying)
-we had lunch at The Slanted Door which was awesome, the tuna collar is to die for, but obviously there are tons of great restaurants. Just go ahead and plan some meals and sight seeing (I love the idea of taking your photographer around for the day, in which case call me, I’m a wedding photographer now :)), but have time to relax too. The process once we had the right paperwork was pretty simple.

Feel free to contact me if you have more questions!
-we took a cab from place to place and they seemed easy to find, but our hotel was downtown. We did walk to the city hall which was less fun since a homeless man tried to choke my husband (terrifying and sad), but I think a cab is the way to go.
-in San Francisco you can get some really neat photos over by the wharf in the market (we had champagne there)