Planning to go to CA on family vacation with 2 kids (13 & 8)in mid-August. First time visit to CA.
1)Any recomendations on nice hotels in LA, SF, SD and itenary for ~10 days. Planning to fly to SF and drive down to SD or opposite. BTW: is San Diego worth a visit? Plan to visit Holliwood.
2)Any recommendation on where to stay during the drive from SF to LA?
3) Are beaches good and warm in CA in August?
Any recomendation on nice beach anf hotel?

If you type in California under "Search this Forum", you will find many suggestions and itineraries that have been written in the past couple of days.

Regarding #2, are you planning to drive along the coast from Big Sur to San Simeon, or the fast, boring drive down the I-5 to LA? The Coast route will involve an extra day. Do you want to see Hearst Castle, or bypass it.

Your children will definitely enjoy San Diego as there is much to do and see. The beaches are good, the water isn't as warm as you may expect, but kids enjoy it. August is a good month to stay along the coast.

the water temp in southern california in august should be about a perfect 66-70 degrees water temperature.

as far as sd goes, that's a tough one. if you're interested in some of the sd particulars like the zoo or sea world, etc., then sure it's worth a visit. but on the other hand, as a first time visit to california, you'll see and experience enough between sf and la that san diego would be nothing special. not to say that sd is not special in it's own way (i'm from here, so i'm not dogging my hometown), but i'd take my time between sf and la instead of going to sd for the sake of going to sd.

anyone that tells you the water temp in august is cold, likes their pacific ocean like a luke warm bathtub. sorry, this isn't florida(we don't have the giant cockroaches, the trailer parks and trailer trash - ok, maybe we do.. , nor water temperature to prove it).

Check car rental rates first...sometimes one-way rentals are half-as-much going north than going south.

San Diego is very expensive in August but a bit cheaper weekdays. LA and SF hotels will be cheapest on Fri Sat Suns.

Carmel Mission Inn is a nice place to stay and with kids that age you should visit Pt Lobos State Park. They can read the legend of the Lobos gnomes on the drive to the park.

hibrentwood is a nice family hotel near the Getty Center and close to Beverly Hills, restaurants & short drive to Malibu Beach.