There are 2 left luggage counters at Suvarnabhumi Airport and both are open 24 hours. One is located in the Arrival Hall on level 2 near the escalator behind Exit 4. The other is on level 4 in the Departures Hall near Entrance 4. Both are run by Chubb, the international security firm.
For storage charges, each item deposited is charged at Bt100 per 24-hour period. All items are x-rayed before acceptance, and high value items on the list including jewellery, watches, antiques, gold, cash, credit cards, perishable goods, fragile articles, electric appliances, mobile phone, shaver, CD player, MP3 player, portable computer, camera (film or digital) or VDO camera must be removed and retained by you, before your bag will be accepted.
It would take you about 30 minutes to complete the arrival process for a domestic flight, then on the way back, you will need 2 hours to reclaim your luggage from the counter and proceed to check-in for your flight. As a result, you will have five hours to spend exploring the city before leaving. The new Airport Rail Link will help shorten the travelling time to the city as it takes you only 26 minutes to connect to the BTS train at Phaya Thai Station. I’d recommend taking the Airport Rail Link into town, as there is nothing much to do around the airport. Once you are in town, you will have no problem finding things to see, do or eat. You can visit Jim Thompson House (www.JimThompsonHouse.com) on Soi Kasemsan 2 opposite the National Stadium (BTS: National Stadium) or Suan Pakkad Palace Museum (www.SuanOakkad.com) which is located on Sri Ayutthaya Road just near Phaya Thai BTS Station. Both places are lovely for a stroll in the afternoon and feature traditional Thai houses in their compounds. Suan Pakkad Palace Museum has a group of Thai houses with covered hallways between them as well as Marsi Gallery at the Chumbhot-Pantip Centre of Arts.
If you have time, spending one or two hours enjoying a traditional Thai massage before taking the train back to the airport is quite a good idea too.