So I have to admit, I've never flown through either airport but every time there's been a Philly flight I've considered, there's always been a note that indicates we'd have to 'change terminals' which, due to time considerations, has caused us not to book it, so you might want to chech that out, too. We've also been warned to take weather into consideration if considering Philly but we always go to SXM in April and snow has never been an issue for us.