So we have a trip to Mt. Whitney in a couple of days. There were originally 4 of us, but one guy had to back out. The guy leading most of the pitches has never climbed with double ropes. Is having the second climber ascend on a bight the best option? If not, do you have other suggestions?
Yeah, my suggestion is that the East Face of Whitney is probably not the best place for you to figure this out.
You've got a few options.
The leader climbs with two ropes. Can be two singles, twins, or even doubles. The leader does not have to use or be familiar with the use of double rope technique. He can use twins and clip both ropes as if they were one, or be belayed on a single and just clip the second rope through gear as directionals. The leader would then belay both up at the same time or one at a time if they were not able/familiar with how to do so.
The second can trail a rope to the 3rd and then belay up the 3rd.
As you suggested, the second can clip in to a bight of rope just above the 3rd. It helps to tie the bight as a "tail" long enough to give the 2nd some room to move without pulling the 3rd around.
There are obviously advantages/disadvantages to each method. But, like I said, Whitney is probably not the best place to figure this out. You should already know what the hell you're doing before you get there.