get a microscope from radioshack, and take a peek at the trichomes (crystals) when the trichomes turn cloudy, the plant is ripe, thc is at it's max. that is what you are looking for. to acheive the couch lock, let plant go until at least half of the crystals go from cloudy white to amber/red/purple.

thc gives you the "head" high.

degraded thc gives you the "couch lock"

it is very true that most of the "feel" of the high is strain dependent, so.....

hope this helps,

love, kp