I've flown red eye SFO-IAD countless times. I love that it's possible, but it's not the best choice in all situations. It works well when I need to get east half a day sooner. I can meet someone in the morning, or drive/connect somewhere and meet before lunch, etc. But the idea that it really saves a day is misleading. I don't sleep well on planes, even in business/first, so I run out of steam during the day after I arrive. That may be a reasonable tradeoff on a leisure trip but it's risky on a business trip.