UV protection

Aloha. Just had a quick question and this seemed like a good place to maybe get some info. Swam competitively growing up and through college...then got away from it for a while. Been back into lap swimming for a while now and been doing some open water as well. Growing up on the east coast the open water stuff i did was limited to a handful of 1 or 2 mile events in the summer. Since i wasn't in the water that long (and I was young and carefree) UV protection wasn't much of an issue. Now I live in Hawaii and some of the open water swimming I've been doing has me in the water for hours not minutes. Most of the people I swim with aren't as concerned with the sun as I am so they just opt for good sunscreen. I use Watermans sunscreen which is great for surfing and has done a good job for the longer swims as well. However I've been looking for a suit w/ more coverage then a speedo/jammer b/c I would just feel more comfortable w/ the physical protection. I recently tried doing a 6 mile swim w/ a rashguard that i usually surf in. Felt fine for a while but eventually ended up giving me some pretty bad rash around the neck. Anyways any suggestions on a comfortable suit that would provide decent coverage/uv protection? I have been looking at some tri-suits. Is that a good place to start? Thanks in advance for any advice.