Humbolt County is great, but you wont be swimming much. Stensin beach is the farthest north that the swimming is any good, and then only in the heat of summer. i was raised in the east bay area and spent many a day at stensin beach and another south of it called Fort Conkite, or pebble beach as known by locals, am not sure if it is open anymore. If money was no object i agree with the carmel area or even further south, depends on how much beach time you want. Personally, i would change the beach to the lakes in Northern CA, Shasta, Trinity, Almanor or even Folsome. I love the mountains and fresh water fishing/skiing. The schools are not full of gangs this far north either as far as i know.