I am planning on adding a sub panel to my workshop where I plan on having a 20 amp breaker for the air compressor, another for the window AC unit, and a 15 amp for 6 outlets and another 15 amp for 3 fluorescent lights. I plan on running the wire from the main panel to the sub panel through conduit around the base of the house for approximately 40 feet. What type of wire should I use?

The wiring size depends on what breaker you decide to feed the sub panel with... IE... a 60 amp breaker would require #6 copper wire. Are you aware of the grounding requirements for a sub-panel and the type of panel to use? Are you going to have less than 6 breakers in this panel?

I will be sinking an 8' copper rod and grounding the sub-panel to it. I will be running a total of 5 breakers so a 60 amp breaker at the main panel and #6 wire should work.

Just an FYI, if you run electricity out to your shop, you must install a light outside the entrance door.

Also, all receptacles in the garage must be GFCI protected and I strongly suggest that you use 20 amp for your receptacles, not 15 amp.