I shoot for a minor league football team, and do a lot of walking up and down the sidelines and sometimes from just outside the endzone so I can look downfield when the players are at the line and I want to get faces.
I almost exclusively use my 70-200 f/2.8. I have a prime, but I don't use it at games unless there's going to be a team photo, and then I'd be more likely to use my wide angle zoom. I'd prefer to have a 24-70 f/2.8, but I just have a kit wide angle, which is adequate.
If I do use two cameras, I have a wide angle on one and the longer lens on the other, but only use the wide angle for sideline shots of the players when they're waiting to go onto the field.
In most cases, shots of the game itself are done with the long lens (the 70-200mm).
and if I were shooting from the stands, I'd be using my 70-300mm, although the aperture isn't as nice as the f/2.8, so I might have a second body with that, just in case.