Yep, going to divide it into four quarters. Each quarter is going to be (mostly) cut into two parts which are themed like so:
Alpine and East Asian Winter (think monkeys in hot springs)
Pre-Rapaelite esque Woodland and
?? god knows what
South Asian Jungle and European Palace/Gardens.
Eastern Europe square (might end up being my main street too) and Pacific Northwest Twin Peak-lite.
As far as transitions go, I'm going to keep similar themes close (like Alpine and Twin Peaks) so the transition isn't too jarring. In the middle there will be a flower garden compass type thing, however since theme parks usually have a big building as a central piece I might enclose this in a castle.