Originally Posted by
pigzilla
Generally you have to book the one way in a single class. Needs to be business or economy all the way TPA-IAD-GVA. The only way to book different classes at time of booking would be to cancel the current reservation and book separate PNRs for TPA-IAD (economy) and IAD-GVA (business).
If you want to go the upgrade route you could book in economy and then use the cash upgrade option in the reservation for the IAD-GVA segment (not sure how you can find out the upgrade amount before the fact). Or if there is PZ/PN open on IAD-GVA, you could rebook the entire segment in economy and then upgrade IAD-GVA with PP or miles (assuming you can use PZ/PN).
My advice would be to not risk it and just stick with the early flight. Have some early morning PDBs to compensate
Sorry, but definitely not true on UA that you need to book separate PNRs for separate classes. Can easily be done when there's no business availability, subject to fare rules, which are usually quite permissive here, unlike some other airlines (BA comes to mind).
The OP's bigger issue is that this sort of change before departure is going to trigger a fare recalc, likely losing A/P, and may result in a huge fare increase. If he has status, then an SDC (with or without downgrade) could work within 24 hours. Without status, and assuming the A/C to make this change is high, this is going to be a tall task.