Some California April trips I've enjoyed, good for a small C or a TC or B:
Coast Ranges (between LA & Santa Cruz)
Trip report & photos here:
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28268422.cfmhttp://www.rv.net/forum/index.cfm/fuseaction/thread/tid/28268422.cfm
Hwy 395 side roads, Ridgecrest to Bishop. Often there are lots of wildflowers.
2012:
https://picasaweb.google.com/CVKSmith/CAHighDesert420122011:
https://picasaweb.google.com/CVKSmith/Hwy395EasternSierraApril2011coast: San Luis Obispo, Santa Barbara, and Ventura counties
2009:
https://picasaweb.google.com/CVKSmith/CACentralCoastPlusMore