Mount Palomar's wedding facilities are separated nicely from their winery operations so there is definitely a sense of privacy. You do have the choice of a barrel room reception or their garden. Both are quite nice and photograph beautifully.
There are only a few Temecula wineries that get good sunsets. Mount Palomar is one of them. The property is located high on a hill so there are no obstructions. I'll typically tap the bride and groom on the shoulder during dinner for a quick 10 minute shoot in the vines while the sun is setting.
If you choose to have your reception in the barrel room we'd highly recommend uplighting from your DJ. This room, in particular, is magical when lit well!