I usually just ask the valet how familiar they are with Roadsters (or Model S when I'm lucky enough to have one for a few days) - some are, some aren't. If they aren't, I usually can park it myself (especially if plugging in) and then hand over the keys. I'm always happy to show them so they know what to do the next time.
You're new to the forum - there's a lot of California-specific information in the regional area.
California