Mongoose,
I think, if you are introducing someone to hiking and doing a night hike, your best option is to go to the old toll rd. off rt.124.
Parking there for me has never been a problem. I don't think anyone's going to be looking for you until the morning shift comes in. I've left there close to midnight on several occasions.
Although, the white dot and white cross trails are are the most direct route,
they might be a little hardcore under headlamp.
There are a few " pole-hucking spots " if you carry them.
Might not be a good thing to do with a novice.
My suggestion is to park at the old toll rd.
You can either hike up the road or take the old halfway house trail, which runs paralell to the road, until you get to a major junction, just above the halfway house. At this spot you have several possibility's. If you get there early, check out the cliffwalk. The most direct route is the white arrow tr.
Coming down, I like to take the smith summit tr.over monte rosa, and back to the old toll rd.It's very little out of the way.
From there, anyone who was having a tough time will be releived to see a nice gravel road to follow down.
Steve