Diving local in PNW? Talk to your local dive shop. Local shops are a great local resource. When I travel, I research out and contact local dive shops in the location where I will visit for info.
I'm betting that if you are going to do local diving and want to enjoy it, there will be a drysuit involved. If you are just doing local refresh dives before heading off to a vacation in a warmer location, than a wetsuit will do.
14mm on the core sure sounds warm. But a 7mm full suit can be much warmer. How? Watch out at the arms, neck, and zipper. If they seal decent and don't allow excessive flushing of water you will be warmer. One of my coldest dives was in an otherwise warm wetsuit. Someone was helping me into the wetsuit and they folded the back of the hood instead of making sure it was flat. Made a channel smaller than that of your little finger. It just let cold water right into the back of the suit. That water flushing through the suit will negate the insulation factor. So I am going to say fit is way more important than if it is 1 or 2 piece.
There is also a semi-dry option. It is still a wetsuit. But like I was mentioned above about slowing waterflow the semi dry uses seals.
I would still recommend a drysuit. I live in AZ and my local ocean dives are southern California. I still use a drysuit. Last year I ran it until July. Last weekend I was out at our local lake, everyone of us was in a drysuit.