Decided that spending two grand for lodging going to lake Tahoe was nonsense so the vacation will now be driving the Pacific Coast highway and obviously stopping and doing things and seeing things along the way.

We will be driving it south to north. Flying into San Diego or LAX & leave from San Fran

Anyone have suggestions & ideas on what to see/do & where to stay along the way?
Also, where to rent a nice convertible for the trip from?

Solvang is cool.

Cambria is cooler.  :-)

Don't miss Hearst Castle, just north of Cambria.

My advice is start in LA, not San Diego, and head north on Hwy1/101.  The trip from SD to LA is not what it once was.

All the major rental car companies offer convertibles - Mustangs, Jaguars, BMWs, Maserati,...  You can also rent exotics or even motorcycles, if you'd prefer either of those.

If you’re coming to San Diego.

In San Diego go get a burger at Hodad’s in Ocean Beach, then drive up to the cross/military veterans monument at Mt Soledad. Spectacular views of San Diego and surrounding area.  

Drive coast highway La Jolla, Del Mar, Encinitas (stop n check out Swami’s), Carlsbad, into Oceanside.  

Check out the Oceanside pier and get some donuts at Parlor Donuts they are excellent. It’s just a block from the pier.

Surf museum is nice and right near the donut place.  

Check out the Oceanside harbor too before heading north. There’s usually a bunch of sea lions hanging out. There’s paddle boarding/kayaking available in the harbor.  

If it interests you, the biggest of the Catholic California Missions is here in Oceanside. I’m not sure if the museum/tours are going though.

From O’side you’ll take the 5 to San Clemente where you can pick up the coast hwy again.

Check out the beach/harbor at Dana Point.  

Someone else can chime in with stuff to see and do up that way.

If you’re spending a couple days in San Diego hit the midway museum, balboa park, Coronado, Old Town, and take a quick trip into the mountains to Julian.

Hwy 1 is closed south of Big Sur - from what I've seen/read it's not going to be open for a long time.

South of Morro Bay PCH is "meh" - Dana Point/Newport is okay, Santa Monica/Pt Mugu is okay, Gaviota Pass/Lompoc/Pismo Beach is nice but overall there is way too much traffic & development south of Morro Bay for me.

IMO, PCH north of the Golden Gate Bridge is a much more scenic and enjoyable drive.

Well, you've got Highway One (PCH) and or 101.  From Dana Point/San Clemente south to San Diego, I don't recall if they call the old highway 1 or 101.  I-5 has replaced it for the fast ride but aside from Camp Pendleton, I believe you can take the old highway to La Jolla?  Maps will lay it out.  Agree that the old beach towns have been kind of overtaken by recent development filling in most of the way.  I don't believe I've followed much of the old road for years.  I-5 goes inland at San Clemente/Dana Point and San Juan Capistrano.  PCH from Dana Point north to Long Beach is close to the coast and there is some ocean view driving, again, kind of filled in over the years.  At Long Beach it trends inland and until Santa Monica is pretty much all street driving.  At Santa Monica it returns to mostly beach side but parts of the Malibu area it's in from the coast a ways.  Then coast side to Point Mugu.  Inland to meeting up with the 101 in Oxnard, then close to the coast through Ventura.  The 101 hugs the coast until Santa Barbara then back to the coast not too far out of Santa Barbara.  1 does split off a few stretches of old road along the beach, old road, several state and county parks/beaches.  At Gaviota, 101 goes inland.  ! branches off but also remains inland until close to the Pismo area.  Jalama Beach is a traditional beach park a nice but kind of long drive from and back to the 1 south of Lompoc.  There is a lot of undeveloped territory past Santa Barbara.    I believe but don't recall for sure if the 1 and 101 are together all the way from Pismo to San Luis Obispo.  It goes inland between Pismo and San Luis Obispo.  The 101 is essentially inland all the way from there to San Francisco.  At San Luis Obispo, the 1 goes to the ocean at Morro Bay thence north to San Fransisco, pretty much coastal all the way.  I think the strech of 1 from the Montery area to San Francisco is much more like most of it used to be, not filled in, not over developed, etc.

However, as noted, while the stretch from Morro Bay to Carmel/Monterey is perhaps some of the most magnificent coastal driving, it's blocked by a washout and you can't drive all the way through.

Things to see and do?  L.A. sort of sucks. however, if interested, and things open up, etc., there are world class museums, like Getty, Huntington Library and Gardens, the Autrey - western and film history, a couple of state and county museums near Exposition Park - next to the Colosseum adjacent to USC just south of downtown.  Hollywood sucks but there is the Walk of Fame, the Chinese theater, Griffith Observatory scince and space related, a the night view is usually incredible, it overlooks most of the L.A. Basin.  Popular, hard to find parking, look up visiting instructions etc.  Hollywood Bowl, check the season.

Most of the Spanish colonial era Missions are quite close to the 101.  Historic, "romantic," controversial - Spain used the missions to get a foothold into California to counter Russian (from the north) and other European colonial (fur and trapping interests, too) attention.  Simplified, conversion of the Indians would provide for Spanish settlement/presence in the area.  The actual history is quite gritty and not all that idyllic in some ways.  while mythic and told of in stories, the California gold riches were not really "discovered" until after the War with Mexico. so, apparently no gold, Spain didn't send in the conquistadors.  Just a limited military and missionary presence.  The missions can be interesting to visit, some are surrounded by their name sake towns and cities, some still rather isolated, some  just ruins, others reconstructed and active local parishes, or a state park.

North of Santa Barbara, the Central Cost, agriculture and wineries, Santa Ynez Valley is the first big wine area, then around Paso Robles, then near Monterey and some south of San Francisco.  Lots north of San Fransisco.  Santa Barbara and Santa Ynez valley are kind of weekend resorts for the L.A. area although Santa Barbara is a large city on it's own, too.  Monterey and Carmel are similar, quite nice on their own and weekend close to the Bay Area.  Montery's aquarium and Fishermans Wharf/Cannery Row are popular but not as slammed or quite as awfully touristy as Fisherman's Wharf in San Francisco.  Coastal redwoods can be found from Big Sur or so north in the coast mountains.  Some awful fires throughout much of the area so check if planning visits.