
Nothing ventured....nothing gained!
From my experience (10+ with British Airways) you've got 2 hopes...and one's Bob ;)
Even staff cant get upgraded these days.
In the glory days when I first started flying (as Crew) it was par for the course, most flight's seats were over sold but upgrades tended to be done at the gate (not at check-in as the flight had to 'close' to know how many of the oversold seats had turned up, and this generally worked well as many business traveller tickets were open and so chopped and changed at last minute..so pax loads shown pre-checkin always changed by check-in close) generally the Gate staff would choose 'business' looking passengers to up-grade (men in suits!) Then with the advent of 'loyalty cards' Gate staff were instructed to look for 'BA Gold card' holders and upgrade them. (which I always found unfair as these people tended only to be so loyal because it was their firm rather than them that were paying for all this 'loyalty')
I lost count of the amount of Business travellers who cottoned on to this and when travelling for leisure (paying for the ticket themselves) would buy themselves a Club or First ticket and their wife an economy ticket! then get on the aircraft and wave their gold card at me and demand that their wife be upgraded!
Nowadays Gate staff/check-in staff and crew are not permitted to upgrade passengers (most flights will not even recieve the catering for any extra)
Alot of Airlines now advertise upgrades to be paid for, Free ones are few and far between.
My advice, take advantage of on-line check-in this way you can view a plan of all the seats on the aircraft and pre choose your seats (so get the exit seats with legroom) they go quick so make sure you'r on-line as soon as checkin starts (usually 12 hours before airport check-in opens) Then knowing if it doesnt work out you have decent seats prebooked I would make sure you are one of the last people at the gate... then if the flight has oversold this is where any upgrades will take place.
HTH?
(Who are you flying with?)