Hi kathyb, welcome.

You write that you do not consider yourself a frequent traveller. Most of us who use miles for upgrades travel frequently, and the more long-haul routes we fly, the more comfort we derive from an upgrade. Do you have a travel pattern where you could use the miles towards an upgrade? If not, will you be able to use the miles before they expire? Or would you consider upgrading the flight to business class in case you bought the tickets (should be in the same mileage region)? Another thing to ask yourself: How long did it take you to accrue these 80000 miles? How would you use them, if not for these two tickets?
I personally would buy the ticket and then upgrade (however, I don't know about your chances with AA/BA), but that's just my $ 0,02...