We're going to be in St. Maarten on May 21st, 2009.
We're planning to check out Maho Beach and hope to see some big planes land.
I'm wondering how much time we should give ourselves(we're renting a car)to travel back to Philipsburg to return the car and make it back to the ship. The ship departs at 5pm. Obviously we'd want to be back to the ship by 4pm, just to make sure we make it!

MAHO is not from from the cruise dock but there may be traffic
I would give yourselves minimum 90 minute to return car & get to dock.
If you are early to the ship you can always enjoy the beach near the dock

Lyn is right - traffic can be slow, plus you will need some time to gas up prior to returning your car. The gas station is just across the street from where you rent.

Sonny