Bummer. I just tried shopping for that flight while making sure I was not signed into united.com, and got this message when I brought up the seat map:

"Seats are not available to be selected at this time. You may reserve your seats at check-in."

When I signed in, I could re-shop for it, look at the seat map, and see all the non-E+ seats in the back as available. So apparently elite status lets you reserve any open seats even after the flight has gone to "airport control".

I don't believe that going to the airport right now will help - you have to wait until the flight is open for check-in.

38,39,40,41,42B are all still open, as are 38,39,40,41H on the aisle sides, 38,39,40C and 38,39,40,41,42,43G on the aisle center section. All I can suggest is to call back and try again, saying that an elite friend of yours saw those seats open and asking if he/she can assign you to one of them. I suppose it wouldn't hurt to mention that you are traveling with your boss who is UGS.

How do you figure you're going to pay $600 to guarantee an upgrade (which would be to business, not first) with miles? I don't fly international a lot, and haven't upgraded, but as I recall you have to be in a higher fare class to upgrade with miles. And you'd need 30,000. You'd need $680 to buy the 24,000 more miles to upgrade, plus you might have to "buy up" your coach discount fare to a higher fare class (minimum of H) which could cost you a few hundred in order to be eligible to use a miles upgrade at all.

http://www.united.com/page/article/0,6722,1150,00.html
"For travel outside of Region 1, upgrade awards can be used with booking classes C, D, Y, B, M and H." If you're in one of the discount fare classes, an upgrade will be impossible with miles. Even if you are, that's assuming that upgrade availability is there (which isn't the same as a business class seat for sale)

If I'm reading the expert-mode availability right on united.com when searching for that flight as an award, award C (business) booking class XC is sold out, but upgrade C booking class NC is NC6 (6 seats available). The thing is, I'm not sure if upgrades with miles book into the "upgrade class" or into the "award class". Since I'm not a 1K I have no experience with upgrading an international flight with an upgrade certificate (an SWU) since I don't get them.

Anyway purchased miles take 3-5 days to post, so even if you have the right booking class and want to spend the $680, it's possible you won't have upgrade availability by the time you use the miles.

I'd vote for buying the E+ access, reserving a good aisle seat in E+ and planning on flying UA more during this year both to earn status for next year and to make the E+ purchase worth it. That's if the calling again with a specific seat# request doesn't work.