IMO, you'd be better off buying those tickets after you get settled into your hotel because the airport is not a pleasent place in which to conduct such business. Furthermore, while there are a handful of travel agents at the airport, for the most part, individual airlines have their own ticket windows (which only sell tickets the given airline's flights); transacting at these windows will put you at an informational disadvantage in cases where more than one airline serves a given route (i.e. most).