Is the food the equivalent of what you'd get for $50 at a high quality restaurant? NOt even close. Attending the banquet helps defray the cost of putting on the event. The organizers have to guarantee a givennumber of plates.If they don't make that number, they have ot pay. (been there, done that at the region 1 convention in 2007).
As far as travel schedules, I hope you've done you're homework. Typically, the room will be closed about 4:00 pm on Saturday and not reopened until after the awards banquet, usually about 10:00 pm. The awards are placed on the tables in the display room and only annoucements of who won are made. Except for the major awards, no one goes up to pick up anything like at your average local event. If you need to leave early, you need to make arrangements with the organizers.
Also, if you are entering anything, you have no way of knowing if you have a chance at an award until the last model is put on the table. Even then, you don't know what the judges will see. Remember, there are no quality requirements at the nats only that you've paid you annual dues. The first one I went to (VA Beach 2002), one of the judges, now a national officer, told me the best dio went to a model with the model with the least eggregious errors.