It's funny - I grew up in VA, sailed Hobies in the Chesapeake Bay and VA Beach and never owned any "sailing clothes" (including a wetsuit) until I moved to Maine after college.
Anyway, I've gotten away from wearing wetsuits, unless it's realatively warm (air and water) and I need the "body armor" on my legs because the wind is up. I find wesuits to be uncomfortable at best and unbearable at worst (when they dry out and you get the rash).
I try to balance being warm with mobility. When you're racing around the buoys, you're doing a lot of ducking under the boom and moving around the boat. That's tough to do when you're bundled up like the Michelin Man.
Anyway, I usually layer up - here's what I bring to a regatta:
Rash guards - short sleeve, long sleeve, full body
Polypropylene long underwear - 2 tops, 2 bottoms (Patagonia stuff is the best, but it's $$) Very thin, very warm.
Drysuit - OS Systems breathable w/ GoreTex feet
Polypropylene socks (to go in the drysuit feet)
Hobie Spray Top - breathable
Spray pants - these are kayaking pants sold at any major sporting goods store (Dick's)
Plain wool hat - like a navy watch cap
O'Neil Farmer John wetsuit
Sailing Gloves - both normal (Harken) and cold weather (Gill)
Teva water "slippers" to cover the drysuit feet.
Sweatpants, sweatshirts, t-shirts
From all of this, I can tailor what I wear to the conditions. My preference is to sail barefoot in shorts and a t-shirt, and I just build up from there.
In most conditions, I'll wear just the spray top with a rashie and a t-shirt underneath.
Sometimes you have to guess about whether you're going to get wet or not; if it's light air, you don't have to dress as warmly, but you could get cold if the wind picks up. It's better to be too warm than to be cold.
You should always wear a hat, especially in cold weather. You'd be amazed at what a difference it makes. The only time I don't wear a hat is when it's blowing too hard to keep one on.