Trips to the concessions stands aren't a big part of my ballpark experience. As long as the Beers of the World vendors continue to work as efficiently as they always have, I'll continue to be delighted on that end.
My whine has to do with my fellow fans, many of whom apparently don't realize that the time to stand up from their seats and go to and return from the concession stands and restrooms is between innings and not anytime the idea happens to pop into their heads. Now I recognize that many, if not most people do use proper etiquette at the ballpark. And I do realize that parents with young kids have gotta go when they gotta go. But one person who doesn't pay attention can annoy a lot of people over the course of 9 innings.
Last time I was at Fenway in 2004, I sat in the right center field, where the aisles are very narrow and the seats elevation is pretty shallow. The ushers prevented people from returning to their seats at will. That isn't the answer for the Cell, but a gentle reminder on ballpark etiquette might not be completely out of line. There is already an etiquette announcement about behavior in the neighborhood before/after games. Perhaps a line or two could be added requesting fans to be considerate of their fellow fans?