Botanizer,
We did Langley on Sept. 13. Based on what I have read on this board we hike at about average speed. It took us about 7 hrs. to reach the summit from the Horseshoe Meadows Trailhead. We were carrying overnight packs, we could have trimmed some time had we been dayhiking. We dropped our packs about 2 miles before the summit at the trail that turns west towards Soldier Lake. Although we went on to Soldier Lake and Miter Basin, I am sure anyone who can dayhike Whitney can dayhike Langley from Horseshoe Meadows. (assuming good conditions, weather, etc.)
The last mile consists of several use trails, you can choose between the "kitty-litter" loose scree or scramble up through the boulders. I found some good information and pictures in the trip reports on this board. You can find them with the search feature by searching Langley and New Army Pass.
The view from the top is phenomenal! Especially the view to the north. It's a great hike, I don't think it is as "dessert-like" as it is described in the "California Fourteeners" book, the first part through Cottonwood Lakes Basin is lush and beautiful. Best of luck