West of the city walls, heading towards Suthep Mountain, is a relatively new shopping area where many small designer shops can be found. It's difficult to say exactly why this area has turned into such a popular shopping district. It's not easy to get to for tourists, but is quite accessible to locals.
The focus for shops along Nimanhemin Road is home furnishings and art. You'll find several shops selling fabrics, candles, boxes of every shape and size, and more. Of special note is Gong Dee, on Soi 1. The shop is an art gallery near the end of the soi that also doubles as a theater.
Most of the original shops in this area are along Nimanhemin Soi 1 and in the arcade across the street. The best way to get to this area is to take a tuk-tuk or taxi to the Amari Rincome hotel, which is on the corner of Huay Kaew and Nimanhemin Roads. Soi 1 is just off Nimanhemin Road behind the hotel (a number of shops are in what were originally apartments attached to the hotel).
More recently, the focus has moved further down the street to a cluster of new arcades built to take advantage of the area's burgeoning popularity. Among these are Moda Place, Tall Teaks and Nimanhemin Promenade, all next to each other about two blocks down from the Soi 1 shops.
If you get hungry, Hong Tauw Inn in the arcade serves excellent local Thai food in a relaxed and friendly restaurant. If you'd prefer a taste of America instead, Mike's hamburger stand also has a branch on the street. Other options include Café Nero, a Thai fusion concept by Black Canyon, located in the Moda Place complex.