I'm using the Minwax spar poly for more and more stuff. I prefer the gloss rather than matte- better UV protection. You can rub out the final coat of gloss and achieve a dull finish, then wax it to bring up a pleasing luster. I don't thin it until the last coat or two. Thinning the final coats allows it lay flatter, the previous 8 or 9 coats provide the build necessary for a finish with "depth".

"You can lead a man to logic, but you cannot make him think." Joe Harz
"Always certain, often right." Keith McCafferty