Santa Cruz [but I have never been to Destin or Old Orchard Beach - in-fact I have never been in Maine but very close by]. I chose Santa Cruz because of several qualities:
1] beautiful beaches [ie Sea Cliff\ Capitola\ Rio Del Mar] with great beach weather [much warmer than San Francisco\ Monterey]. I know from much experience that the water temps in the Monterey Bay are brutal
[it would take at least 10 minutes trying to ease into barely 60F ocean temps - as kids we would stay in body surfing\ swimming for hours & come out blue
2] The boardwalk has the oldest wooden roller coaster in California [the Big Dipper] that immediately drops into darkness & then climbs so high you can see across the bay - great & historic coaster. Santa Cruz & San Francisco used to have fantastic old time Fun Houses with all the stuff you see in old "Little Rascals" movies. Now it's a miniature golf
3] Pacific Gardens is about 5 blocks of outdoor restaurants\book stores - super leftist\ great little shops. The Loma Prieta earthquake knocked down an old unique building but it was build right back as it was historically.
4] University of California - Santa Cruz campus sit's in the redwood foothills above Santa Cruz [Green Party haven
5] Santa Cruz is reliably radical in usual Northern California style
The City Council was so angry over a federal raid on a marijuana farm that they held a "Smoke In" in the city courtyard - tobacco wasn't allowed.
6] Santa Cruz mts has the largest stand of redwoods in Central California w/ great little towns. Areas like Soqual\ Aptos\ Capitola sit on foothills overlooking the Pacific & can see Monterey [30 miles across the bay] because Santa Cruz faces south it is warmer than Monterey or even Salinas.
7] Great surf w/ a long tradition of surfing in California. Santa Cruz sued Huntington Beach for the title of "Surf City USA" but Huntington won. Steamer Lane allows one to watch surfers up close & waves can easily approach 20' in winter
8] California - Santa Cruz is right in the middle. Close to San Jose\ Bay Area. The drive up Highway 1 to San Francisco is magnificent w/ coves\beaches\steep cliffs. San Francisco is only an hour away. Santa Cruz is also close to the wineries in the Salinas Valley. Monterey\Carmel as just across the bay & Big Sur is an hour further down the most scenic coastline in California [where car commercials seem to be filmed every year]. Sierra Nevada are 3 hours east of Santa Cruz for skiing on slopes & in lakes & Yosemite\ Sequoia.
9] Great climate with mild summers\ 70's & winters\low 60. Sunny with morning clouds\fog.