By taxi
A taxi to central Bangkok will cost at least 300 baht. Always insist on using the meter. In the midnight hours a "service charge" may be required, but one shouldn't have to pay over 50 baht extra.
Taxis to and from Suvarnabhumi Airport approx costs 380 baht, Although the touts outside will try and get you to pay 1000 - 1500 baht wait in the taxi line outside the airport and you should be fine.
By bus
Local buses 29, 34, 39, 59, 95, 504, 510 and 522 will get you from Bangkok to Rangsit Future Park 7 baht in the basic non-aircon buses, 18-22 baht for aircon. You can catch most of these from the bus stop next to BTS Mo Chit station. The journey takes 30-60 minutes depending on the traffic and bus the orange 5xx services are faster.
Nearly all central, north and northeast-bound long-distance buses stop next to Major Bowl Shopping Centre (http://www.majorbowlhit.com/), Which is right next to Future Park Shopping Mall as a hub from Rangsit in or out of the main city of Bangkok, and often almost half the bus gets off. And with reason: it's still another hour from here to the city, so this is an excellent place to hop out, stretch your legs and get a decent meal.