There are other things to consider.
You may find that driving a little extra is well worth it if you can cut down on lay-overs & changing planes. By flying into a closer airport you can sometimes save only a hour or two. IMHO, if that means a change of planes you'll likley find that your trip is now longer by flying to the nearer airport because of the added time changing planes.
Also, flying into the bigger airports is almost alway cheaper. (Of course, since Southwest generally likes the smaller airports, flying SW may be an exception)