Just like its Sunday counterpart, Chiang Mai Sunday Walking Street, there you can buy clothes, souvenirs, jewelry... and above all, you can taste the local food with a very wide choice of dishes and street restaurants. Saturday Walking Street offers, I think, a greater variety of Thai dishes than Sunday Walking Street.
Once you are there, I recommend you to visit Wat Sri Suphan (the '' ilver Temple''), which is nicely lit for the occasion.
See here a list of accommodations close to Saturday Walking Street