The Mediterranean!
other than that, let me make you a little short list of suggestions
Visit the Canary Islands, If you're lucky the weather might not suck
Go way out there and see The US eastern seaboard in 1942, sink yourself a tanker or 10
Visit Guantanamo Bay, watch out for MTBs
Do that type IXD2 thing, go to the south atlantic, make a nuisance of yourself around Capetown, refuel at a Milchkuh and have yourself a pleasure cruise up the Brazilian Coast before heading back to France or Penag depending on what takes your fancy
Visit Der Kanal, they have all sorts of Interesting stuff there
Harass the Russians in a type IId in the Black Sea
Umm, the list is near endless, you could always hang the map on a wall and throw a dart at it with your eyes closed, see where that takes you
GWX, there's more to explore....