I would think that if you primarily want length, the you should do as you have been doing, and finish the session by cooling down in a stretched state(which would be cooling down for a 2nd time).
If however your main goal is girth, I would do it the other way around, length work first(ending with a cool down an an extended state) follow by a girth workout(finishing with a cool down in an expanded state).
Your body tends to adapt mostly to the last stimulus placed upon it.
Decemeber 2007: 5.8" BPEL x 4.9" MSEG
Current:-------->7.7" BPEL x 5.7" MSEG (7.2" NBPEL)
Current Goal:--->7.6" BPEL X 5.8" MSEG Do or do not, there is no "try".