Another voice for the U-shape! And extra points if you make it such that the cook can wedge him/herself in by propping his/her butt against one side of the U while cooking in a moderate seaway -- about 24" edge to edge works for us. Attached (if I did it right) is a layout from a much smaller boat that we particularly like in this regard.
I've seen front-loading fridges doors pop open even in a rolly anchorage, so make sure there's a positive fastener, and lips on any racks inside to keep foods from falling out. About planning your storage locker layout - you don't say where you'll be sailing but condensation is always an issue - make sure that there's at least some locker *not* against a hull for storing things that need to stay very dry (bulk flour, for instance). And you need less area for stowing staples right in the galley than you think - unlike on land, where all foodstuff goes in the kitchen - here, you only keep small quantities of things in "high rent" space and keep your back stock elsewhere. This will help keep your galley tight (ex, we keep a small 6-oz bottle of cooking oil in a spice locker by the range, and refill it from a 1/2 gal bottle in the "pantry" in a less convenient location under the settee on the opposite side of the boat.
We tried a PUR filter but it didn't seem to work very well in the somewhat lower water pressures on the boat, clogged up quite quickly. Their customer service was great but the product just wasn't designed for our application. We ended up with a Culligan RV filter with somewhat bigger pore size that's working better.