I can't speak from experience with the C-Dory (yet!), but I did comb through the archives when I was preparing to purchase an anchor. It seems like a common "good" size for a claw, plow, or similar-shaped anchor is around 15 pounds on a 22, with the occasional person having a 20-pounder.
One comment that's not specific to one boating area, but just what I've noticed in general: These days it's hard to count on 7:1 scope, unless you only boat in really out-of-the-way places, due to moorings, other boats, etc. In other words, it's nice to have a setup where you feel comfortable on 4:1 or 5:1 if possible. (That said, with such a shallow-drafted boat, it's probably possible to get to an uncrowded spot even in a crowded anchorage.)
I like Danforth style anchors in sand, if you aren't going to leave the boat unattended. I had planned on one for my second anchor (or a Fortress), but for now I jumped on a great deal on a Lewmar claw (Bruce clone), even though it's not going to be as easy to stow, and somewhat duplicates the type of my primary anchor. For my primary setup, after poring through the archives here, I went with a Manson Supreme 15# - first time I'm trying one of those - plus 25' 1/4" G4 chain and 200' 1/2" brait line. I had a hard time not upsizing everything, but forced myself not to
My setup has not yet been tested though, so take my thoughts for what they're worth.
Sunbeam