Late reply, but whenever I purchase tickets to any stadium, I check the section's view on
SeatData - Home Page
Love that site.
Just visited Lincoln Financial Field over the weekend for a Monster Jam show for my son and I have to admit, GREAT facility. The team and fans are trash but they have a nice building.
FedEx - click on section for view.
SeatData - Washington Redskins - FedEx Field
I believe, if you're buying through TicketMaster at least, they tell you at checkout if the seat if an obstructed view seat.