Those 777's seat 12 in first, 49 in business, and 197 in coach. And business is ALWAYS full. Always, always!
If you can't fill up a 12 seat F/C on a 777...then something isn't right.

Then again...using a 777 on a domestic run????
I know, if UAL is doing it....it's gotta be right.
Usually there are 2 or 3 seats left in first.
If I was on a business trip.....I'd feel better getting First Class. If a 777 goes out with a few open F/C seats....then a few of your premium customers didn't get an upgrade. Not good for the J.D. Power voting!
The only caveat...if there's some weird deal where B/C has better seats...food...drinks....service,etc...than F/C. Nothing would surprise me these days.