Image by clement.cc via Flickr
Two of the best locations to see Monarchs are Natural Bridges State Beach in Santa Cruz and the Monarch Sanctuary in Pacific Grove.
Below are links to both of these sites as well as a link to some lesser-known locations. I have also included a posting from California Photo Scout on suggestions for photographing Monarch Butterflies.
Pacific Grove Monarch Sanctuary: http://www.ci.pg.ca.us/monarchs/default.htm
Natural Bridges State Beach Santa Cruz Docent naturalist led tours of monarch butterflies wintering in Santa Cruz are held 11am & 2pm weekends, through Feb 12 on Saturdays & Sundays. Phone: (831) 423-4609 http://www.santacruzstateparks.org/parks/natbridges/index.php
Posting at Nature Photographers Network-California forum of lesser known locations in the Santa Cruz area to find Monarch Butterflies : http://www.naturephotographers.net/imagecritique/bbs.cgi?a=vm&mr=62330&CGISESSID=bad04b4b772f46c62395c00dc5d93a1d&u=2653
Monarch Butterfly locations (both popular and lesser known) includes site information, website link and phones: Chasing Monarchs along the California coastline http://rosevilletoyota.sensibledriver.com/articles/chasing-monarchs-along-the-california-coastline
California Photo Scout article on photographing Monarch Butterflies: http://ca.myphotoscout.com/2009/01/21/monarch-grove-sanctuary-butterflies/
Natural History Wanderings 
That Roseville Toyota link is most curious. I’d never think that a car dealership would have a very nice article on monarch sites. Did your friends see monarchs when they came this way?
LikeLike
By: Katie on December 4, 2010
at 8:36 AM
I was also quite amazed to see an auto dealer post a quality article about monarchs. I don’t think they saw many butterflies on their trip.
LikeLike
By: Sandy Steinman on December 4, 2010
at 9:16 AM