I am in the final stages of building my kitchen island:

http://tinyurl.com/3djl4yl

That is a Sketchup file...

Anyway, I am doing the front of it today, creating the face frame. I will have 4 drawers on top about 3" x 17" each, side by side. Then 2 very large drawers below, on on top of the other about 36" by 9". The depth of the inside of the cabinet will be 20 1/2" or 21 3/4" depending on if I use 3/4" ply to back up the face frame (don't know if I need to; another question). My question is what to do for the drawer slides. I want full extension, preferably the "soft closing" type, but I don't want to go broke.

This is my first piece of cabinetry, so any advice is appreciated