Given you have a tight connection, I would either pay for closer seats if its only 15 bucks each OR you may be able to request a seat change free of charge at check-in or via a gate agent at the gate.. While DCA is indeed easy to navigate, NOTE that there is also no guarantee that there wont' be unplanned delays upon arrival, especially during peak times, on NUMEROUS occasions I have sat in planes on the tarmac at DCA waiting for gate assignment and have witnessed other passengers with connections visibly distressed and barely missing their connections.. Just something to keep in mind..