We fly in to Long Beach early 10/2 and leave early afternoon 10/4. How much scenic beach driving will we be able to do? Is it realistic to head up to Solvang/Santa Barbaara the first day, then down towards Laguna the second or is that unrealistic? How can we stay on the PCH as much as possible and where will we hit traffic? thanks! Also, any ideas for beach hotels that are not too small or too remote? We have a grandma with us.

Where are you flying from and how early?

It seems when we fly from Florida to California we invariably get a 6 or 6:30 AM flight so we're up by 3 or 4 to do it. Add the 3 hour time difference and by 5 PM in California it's like having been up since midnight or 1 AM. I think I "crash" more often my first day in California than flying to Europe.

I'd be more tempted to just go to Laguna the first day and do the 'northern' trip the next day. But of course that may depend on how early you need to fly out.

I'd pick one or the other..
With a Grandma, I would choose Solvang/Santa Barbara..does she get around well?
I love Laguna Beach and totally agree with Neo on the crash mode after flying from the east to west coast.
What's your budget for hotels?

I would skip Santa Barbara and head straight for Laguna Beach. SB is really lovely but it is a long drive and you just don't have the time.

Laguna is great for older people (as well as everyone else) and has some nice beach hotels. The Surf and Sand is my #1 favorite. Its rooms are right on the sand, which is strangely hard to find in So Cal. It is not super expensive but it is on the pricey side. If you can't swing it, at least go there for lunch. Its dining room is right at sea level and the food is terrific!

From Santa Monica to at least as far south as Seal Beach, you are going to want to avoid the PCH.

I agree that going to Laguna on the first day and Santa Barbara on the second day would be best. For that type of trip I don't see any point in staying at a beach hotel. The Ayres Hotel in Seal Beach would be a good choice, considering the logistics, esp. if you are leaving from LGB in the morning. That hotel is at the Seal Beach Blvd exit of the 405.

But I advise skipping Santa Barbara to cut down on driving and allow you to enjoy the south coast. Then staying at a beach hotel makes a lot more sense because you would have time to enjoy it.

For scenic you'd probably do best to head north on the coastal road through Malibu, Oxnard and then up to Santa Barbara. But you're talking weekday traffic so your timing getting through L.A. would be critical.
If you choose SB, stay there for two nights...dont'try one night there then one night LB.
Montecito Inn just south of SB if you choose to go north, Laguna Riviera hotel if you choose south.