How much money per night do you want to spend on a hotel room? Kids and younger tourists usually head for Khao San Road. But not too many of them have an interest in that much shopping. (No rail service available.)
Shopping, maybe for the purpose of reselling in your own country, consider the Pratunam area. From the airport it is possible to use the Airport Rail Link (commuter train) to take you to Ratchaprorop Rail Link stop. Walk from that stop to this hotel. (No rail service after midnight.)
Lub D Hostel. Two places located not that far from the Skytrain route.
Bangkok rail service routes.
Pratunam shopping. Lots of street vendors and wholesalers.
If you want to shop indoors maybe stay near MBK.
Street vendors, malls, nightlife, good restaurants available on Sukhumvit Road. Streets still alive at 2 a.m. with tourists and locals walking about. Easy access to Skytrain.
P.S. If you plan on all using the same hotel room there will be extra charges for extra people. Extra people in a hotel room use more towels, make a bigger mess, etc.