I suppose for me, it goes way back to my childhood. My father was a radioman PO on a baby flattop in the Pacific during WWII. His ship even got hit by Kamikazes. That's how my interest in the PTO started. Not to mention that the largest naval battle of all time was fought there, and by the largest navy that (probably) ever existed, the U.S. Pacific Fleet. I sometimes like watching the game as it interacts with it's own AI during different battles/scenarios. I also seem to be a SS junkie, though alot of my SS are uninspiring.
During the early part of WWII the u-boats had their run of the Atlantic, like shooting merchants in a barrel. Took awhile before the allies got their sh-t together. After which, most of the u-boats were withdrawn from specific theaters.
IMHO, the Pacific offers more of a challenge.