Hey Bryan,
Good luck on the trip. After all the hikes and climbs I've done, Half Dome is still my favorite. I've climbed it three times, all as dayhikes from Happy Isles.
As others have mentioned, start as early as you can, which not only will give you more time to ascend gradually and watch your pace, but will importantly get you in position to start up the cables when fewer people will be on the trail.
Read the book "Shattered Air" before you go:
http://www.amazon.com/Shattered-Air-Account-Catastrophe-Yosemites/dp/1580801420If anyone in your group feels the cables are not for them, then you can always take a side trip up Clouds Rest which makes for a nice, less traveled alternative.
