As the librarian of the Carlsbad History Room, I belong to an organization called CINCH: Council Interpreting North County History. Every time I attend a meeting, I am amazed at the wonderful programs, museums, archives, and collections available to us in North San Diego county.
I've compiled a list of some of the organizations & museums in North County that are worth a visit and have great things to do with your children, family, and/or friends! Many are free or low cost to visit. There are many seasonal offerings, ways to volunteer, Boy & Girl Scouts opportunities, classes, camps, etc. For a more complete list, stop by the history room at the Cole Library for a Historic North County San Diego brochure. If you don't live in our area, there are sure to be many similar organizations, museums, etc. in your area.
*Carlsbad Historical Society Museum, in Magee Park in North Carlsbad. Wonderful rose garden & afternoon tea (by appt.), in addition to the museum- http://www.carlsbadhistoricalsociety.com
*Barrio Museum, a wonderful small museum with great old photos! Open by appointment- Contact Ofie or Connie @ Lola's 7-Up Market & Deli @ 760-434-2191
*Craftsmanship Museum, new in La Costa- http://www.craftsmanshipmuseum.com
*Leo Carrillo Ranch Historic Park, off Melrose Ave. in La Costa- http://www.carlsbadca.gov/services/departments/parksandrec/parks-facilities/parks/Pages/leo-carrillo-ranch-main.aspx
Other North County offerings:
*Antique Gas & Steam Engine Museum, in Vista-really close if you live in NE La Costa. They offer classes on blacksmithing (this class has a waiting list & lots of girls sign up!), antique furniture restoration, weaving, etc.- http://www.agsem.com, and on Facebook: Antique Gas & Steam Engine Museum, Inc., on Twitter: @vistamuseum
*Fallbrook Gem & Mineral Society & Museum- http://www.fgms.org
*San Diego Archaeological Center, east of Wild Animal Park. They have a junior archaeology program! A current exhibit is about a man named Nate Harrison, an former slave who settled on Palomar Mt. His story is fascinating! (http://m.nctimes.com/mobile/article_65f3860f-de3a-56f9-892e-6fc059004307.html) - http://www.sandiegoarchaeology.org
*Poway Historical Society & Museum- http://www.powayhistoricalsociety.org
*Rancho Buena Vista Adobe- http://www.cityofvista.com/departments/parks/adobe.cfm
*San Dieguito Heritage Museum, near San Diego Botanic Garden (Quail Gardens) in Encinitas. They cover the history of Encinitas, Del Mar, RSF, Olivenhain, Solana Beach, Cardiff, and Leucadia- http://www.sdheritage.org/
*San Pasqual Battlefield, a historic state park also east of the Wild Animal Park. They offer living history activities once a month, June-October- http://www.parks.ca.gov/?page_id=655
*Rancho Guajome Adobe, in Vista- http://www.historyandculture.com/guajome
*Mission San Luis Rey, in Oceanside. They offer tours and lectures.- http://www.sanluisrey.org
Additionally, there are the Marron Adobe, in NE Carlsbad on Haymar Rd; and the Rancho Santa Margarita, on Camp Pendleton (open 3rd Wednesday @ 10am for tours).