Heat is the planning constraint here for most of the year. From May into October the afternoon sits high and there is rarely shade where the chairs go. Ceremonies run late and they run short. A seven o'clock start and twenty minutes of words does more for your guests than any amount of water on a table, though put the water out too.
The venues are larger and further apart than they are on the coast. Ranches in Riverside County, vineyards outside Temecula, barns and orchards with room for two hundred people and parking to match. That space is why couples come here, and it changes how the ceremony has to sound. An open lawn eats an unamplified voice, so we bring sound when the venue does not provide it.
Guests drive in from several directions, often an hour or more, from San Diego, Orange County and Los Angeles at once. Something on one of those freeways will go wrong. The ceremony rarely starts on time and it is better to expect that than to fight it. We hold the room while the last cars come in, then begin properly rather than apologetically.
What catches people out is how quickly the evening turns. The valley loses its heat after sunset faster than the coast does, and a ninety degree afternoon can be sixty by nine. Tell your people to bring a layer, and keep something over the shoulders of the wedding party if photographs continue after dark.