I would not risk a 35 minute window to change planes, especially in February. Even a short flight delay would make the connection impossible. Is there an earlier flight from Boston? I think $45 is worth it, but I have missed connections with more time than that, but not in Philadelphia.

I think if it's only $45 more, you should buy the non-stop. It will save you a lot of aggravation and worry, especially in February when the weather can be a problem, too.

A lot of times people tend to be penny wise, pound foolish when it comes to purchasing airline tickets. They inconvenience themselves by either booking flights with multiple connections, circuitous routes, connecting flights with long layovers, or as in your case, connecting flights with very shot layovers in order to say a few dollars when when simple non-stops flights are available for maybe $50 or so more per person.

Those of us who are experienced (frequent) travelers learned long ago that our time is valuable and that the more connecting flights you have the greater the chances there are that something can go wrong.

Do yourself a favor, bite the bullet and book the non-stop flight.

Here are my rules of thumb when booking airline tickets:

1) ALWAYS fly non-stop whenever possible, even if it costs more.

2) If you can't get to your destination non-stop then book the least amount of connecting flights possible.

3) Book the earliest flight possible that way if you run into problems you have more time to figure out your travel options.

4) When ever possible book connecting flight on "one ticket" using the same or partner airlines rather than purchase separate tickets that way if you do miss a connecting flight the airline has the responsibility to get you to your destination.

5) for domestic travel give yourself at least 1 hour between connecting flights. For international travel give yourself at least 90 minutes (2 hours would be better) between connecting flights to allow you to clear immigration and/or customs.

6) If flying in winter add a little extra time between connecting flights rather than opting for shorter times.