Going to DC for the 4 July weekend, I can save a little over $300 round trip on two tickets flying into BWI over DCA.

We would take either the WMATA or MARC from BWI into DC. How convienent is it, and do you consider it worth the savings in flight costs? Do you know if the schedules are the same for holidays? Seems some are weekdays only, but we would fly in on 4 July, how are those schedules?

For work I fly into DCA and am very comfortable taking the metro.