I'll post my thoughts without reading the previous ones. I was there for the NCAA championships.
1. Handicap or almost-handicap access. There were a lot of older people there, including my elderly but not handicapped father, and they had a hard time getting up and down the stands with no rails. There was a meager handicap section consisting of a half-dozen chairs in front of the stands. Access and moving around was very difficult for a lot of people. They need to have some rails or some way to get around for people who have trouble on no-rail stairs.
2. Getting around. Similarly, getting from the main stands (finish line area) to concessions, hammer throw, or to the other side was awkward. You either had to go down, go back up along the track and then around the back, or climb way up and come back down. Don't know how that's fixable with all the necessary finish line stuff right there, but it was a chore for the older people. Maybe extend a walkway over the heads of the finish line stuff.
3. Concession and expo area. It would have been good to have a couple tables or a place to sit down by the concessions. It's crowded there, but maybe they could expand the expo area beyond the current fence line or move the concessions to a different spot.
4. Good things. It was great having all the throws except the hammer inside the stadium. The video screens are really necessary. Track fans like me are used to having access to just about everywhere, so it was hard to watch the throws and jumps from up in the stands. The video screen brought us closer to the action.