Phyathai Station forms the terminus of the Airport Link City Line, where it connects to the BTS Skytrain. A bridge connects the City Line station to the Skytrain station, but there's no common ticketing, so you have to buy a new ticket to transfer from one line to another.
There is not much around Phayathai for the traveller, although the Suan Pakkad palace is definitely worth seeing.
« BTS Skytrain main page.