I tend to wear a good buoyancy aid over a wetsuit when the weather is nice as I know I will be in and out of the water all the time, one of the Baltic Waterskis is good because it has lots of straps for attaching radios, gps and other essential gadgets to.
In less clement weather I go for a jacket with built in floatation plus a manual LJ, that way I have the best of both worlds without the worry of having anything unexpected go off on me.
For really harsh weather, if you must go out in it, then a dry suit and LJ is the only way forward; but then you may as well wear a white Gecko and paint your boat orange.
Baltic Waterski:
http://shop.malthouse-marine.com/ind...=102&parent=31