If you want to order youself (if you are a man) a good suit and couple of shirts then you must visit Narayana Phand. There you can find all kinds of handicrafts and souvenirs. There is a very good basar downstairs where you can find the tailors too.
If you're looking for a nice souvenir, it could be worth your while stopping by this gift and handicraft store. It has a wide range of high-quality goods and it's conveniently located across the road from the World Trade Center. It's not completely easy to spot as it's inside a small shopping arcade, but look just north of Gaysorn Plaza and you should find it.
Items include hand-carved wooden items, ceramics and fabrics. You'll probably get better bargains at Chatuchak, but if you're looking for something specific and/or it's not the weekend, this could be the place to go.
Open from 10am to 8pm daily.
If you want to shop for Thai stuff without having to deal with the heat at the markets and do it in airconditioned comfort, check out Narai Phand. Their prices are very reasonable and you don't have to guess and haggle with the salespeople. I know that's half the fun of shopping in Bangkok, but sometimes, it just isn't if you have to deal with throngs of people or worse, if you don't know how to bargain.
What to buy: I picked up some thai silk shirts, a handpainted thai silk robe, some of those comfy triangular pillows, and a friend bought 3 statues for half the price our other friend got it at chatuchak.
Clothes are cheap in Bangkok but what I would really go back for would be oriental pieces for the home...especially one of those smaller versions of a thai teakwood house.
What to pay: I spent $200 for a lot of good stuff.