Where you live is not as important as the water you will be sailing in. The West coast is warm, but the water is not.
Fit is as important as the thickness. It is easier to get into a slightly oversize suit, & it will be warm on the boat...until you actually go swimming. Then the loose fit allows water to slosh in/out.
All things being equal, a thicker suit is warmer, but anything over 5mm restricts movement.
A shorty is much more comfortable, though not as warm.
I use a 3mm Farmer John in the early fall, using a spray shell for the top, then add the wetsuit top as temps cool.
Finally, the cheapest suits,think Wally World use a poor quality neoprene. It just isn't as warm.
I have 4 or 5 suits, of differing quality & thickness. Obviously the thinnest (2mm), the more it feels like you're just wearing a rash guard.
The best one I own is a Cressi semi-dri 2 pc. It fits very tight at wrist/ankle, & where the two pieces overlap. It also has a snug hood. I tested it one late fall day when the water was 10C.(50F). I could snorkel quite comfortably, & my hair was still dry under the hood. It was also almost double the cost of the cheapies, & harder to don.
There is some good info here;
http://360guide.info/wets…?Itemid=19#axzz3llPlIIvw
--
Hobie 18 Magnum
Dart 15
Mystere 6.0XL Sold Was a handful solo
Nacra 5.7
Nacra 5.0
Bombardier Invitation (Now officially DEAD)
Various other Dock cluttering WaterCrap
--