Spellbee2, do not forget that you can learn to lucid in nREM. It is perhaps more advanced, but do not limit yourself to thinking of dreams as only REM. However, a 90 minute LD is pretty stellar and should be something to make any dreamer very happy.

EarthToKepler, It takes years to learn how to stabilize the dreams. At first you should be happy with even two minutes. You will still be pretty excited even then. Maybe 10-15 minutes with a couple years experience. They do not need to be longer if you are doing great things, like flying. A roller coaster only lasts a couple minutes, but people still ride them.