I went there about 6-7 years ago with the intent of hour building.
I was never told about the marine layer, made most of the time unflyable as it never burned off (Very low 8/8 cloud, below circuit height) Make sure you pick your time carefully. It is known as the May grey or the June gloom. Most years it burns off by lunch but sometimes
.
I managed one trip to Palm Springs (excellent) but made the three hour return trip incredibly expensive to sit on the side of an airfield, worked out to be about #600 an hour, pretty steep for a C-152.
They were very relaxed back then, good bunch of guys, but a definate "air of casualness" about them. I wouldn't go back, based on my experience. Mostly poor flying slot allocation and if you scream loud enough they'd bump someone else to get you a slot. Aircraft had a lot to be desired.
Don't know what they're like now though.
San Diego is a beautiful city and definately worth a visit.