I will be building some shop cabinets in a couple of weeks and need to buy some drawer slides. I have virtually no cabinet making experience, so I am indeed a bit green. If my base cabinets are 24" in depth, how long should my (full extension) drawer slides be? I am guessing 22" slides should work well. Does it matter if the cabinets are to be face frame or frameless (I am leaning towards frameless).

The lengths I can get are 18", 20", 22" and 24". 24" would be too long for a 24" base cabinet, correct? What about 22"?