I would have responded earlier, but I have been away at Galveston for the New Years weekend and my girlfreind will not let me near the computer when we are away.
The info that Jason just posted is spot on as for getting to Lee Rd, however to further expand on this, if you are taking US 59 into IAH, proceed up Will Clayton for almost a mile (stay in the left lane) and you will see a Lee Rd. sign, take the crossover to the opposite side of Will Clayton, then proceed to the far right lane and upon doing that you will see Lee Rd off to your right. Upon turning onto Lee Rd drive for half a mile and you will see the viewing area to your left..and thats it!
As for 'night' spotting, well you can see the planes, though they are not all that well illumnated. The official times that viewing area is open is from 6am-10pm after that the gates are closed. Believe me after dark it gets a little freaky out there ..if you know what I mean, thus the recent viewing times that have been imposed.
This area is becoming very popular especially on the weekends, sometimes it can be difficult to locate a decent place to park.
Anyways, have fun.
"Show me the Braniffs"