Any one know re: AirTran business class upgrade vouchers?

[dedex13]

I've received a couple of business class upgrade vouchers from AirTran but as an infrequent flyer who suffers from anxiety, minor OCD and sometimes severe motion sickness it is very important to me that I am able to board early and have to have a seat in front of the wing. I can't call about the upgrades until 24 hours before the flight so I was wondering if I should go ahead and pay for seats when I book in case 2 upgraded seats together are not available? Or will that not be necessary since upgrades are normally available? I haven't purchased the tickets yet (waiting for the point incentive from the credit card I signed up for), but plan to fly out of BWI on Tuesday, October 29 on the 7:09pm flight.