The Hotel Temecula is pretty darn cool. It's not for everyone but if you are looking for a casual rustic/cowboy theme then this is definitely worth checking out. You have a blank slate here. Bring your own caterer and bar. It's an option that you won't get at the wineries. You'll save a lot of money and you'll be able to customize your experience exactly to your own taste.
Recommendation: The hotel itself is full of fascinating history which has been preserved perfectly by Richard, the owner. Simply ask him about the property and he will gladly give you the full tour.