If you're going on a weekend, arrive EARLY. Parking is
seriously crowded. Definitely arrive before 7:00 AM, and earlier if you can. You could wind up parking down the road close to a mile below the trailhead -- if you can get parking at all. Adventure Pass is supposedly required.
There's piped water available at Sturtevant Camp and at the summit. There's a spigot on the summit that's really handy right on the road. There's another spigot up on top at the pavilion that has the cafe. Here's my GPS track from July of last year:
http://caltopo.com/m/2L70The blue dots on my GPS track represent water. Even though it's not marked, there's also water (and porta-potties) at/near the trailhead, and as I mentioned there's water at Sturtevant Camp. There's also a little pack station that serves hot dogs, hamburgers, cold drinks, ice cream, etc. I usually throw them my business -- and thoroughly enjoy it. It's a pleasant place to relax a bit after a hike. There's also a cafe on the summit, the Cosmic Cafe. It's closed a lot. Best to call ahead and confirm that it's open if you plan on getting anything but water there.
Take note of the exit point from the summit plateau. The little trail saves you a lot of mileage over walking west to where the Mt. Wilson Toll Road comes in.
It can be hot in the lower reaches, so definitely start early -- especially so on weekends when parking is just downright bad.
Oh, and the little spot marked "view" is right off the trail and is worth the extra 50 yards or so of walking (in my opinion), particularly on a clear day.
Have fun. Let us know how it goes.
HJ