Wetsuit help for surfing! (Thickness?)?

Tough question and its really up to you, most surfers have at least a couple of wetsuits available to them for exactly this reason. What I might do since you said you get cold easily would be to get the 4/3. Then you can pick up a 2mm suit (long legs, t-shirt arms) for as little as $90 for the days when it just gets too warm. A 4/3 is fine up into the mid 60's with cool air, but when the days get hot and the water stays in the mid 60's or higher the 2mm should work pretty well. For me a 3/2 doesnt really cut it in the low 50's if the air is also really chilly. I would think that you would definitely want booties with the 3/2. I surf in New England and I was out in Cali (North LA County) last September and the water hit 57, I was glad I had a 4/3 and booties on those chilly foggy mornings, not that it was totally necessary, but just to stay comfortable and to stay out longer.