Just as a thought to the comment about foam tiles being somewhat expensive, what about a painted piece of plywood for the floor? Surely the Vex wheels can work with that stuff, and the price is right.
Going to the footballs idea, what about those hard plastic ones that folks throw into the stands as promos at football games? Cheap, durable, able to be decorated if FIRST wants to splurge, and they'll make all of the folks who have been clamoring for footballs in FRC happy.
Also, this should probably go without saying, but stick with the WildStang-designed field controllers. The system was functional, beautiful on the field (who wants a big beige crate at midfield with all that lexan around?), and displayed all the information we've wanted to know.