There is no need to stay downtown. Save the extra $1,000 to $1,500 that you are talking about and rent a car (if you are flying into town) and park in any one of the many parking garages around the convention center. Parking will run between $22 and $30 a day plus whatever deal you can get on the rental car and then a cheaper (much cheaper) hotel 6 to 15 miles away.
I know this is said over and over again, but lack of a downtown hotel should not ruin a trip to GenCon. I have stayed downtown a total of once in the past and now this year due to a lucky lottery slot and I have enjoyed every visit. It takes a little more planning.
Tired? Go to your car or rest in a chair in a hotel or convention center, there are tons of places to rest in both.
Purchase something? Go drop it off in your car.
I am not trying to convince anyone of anything or say anything that has not been said a million times, but GenCon is what you make of it and not just what happens to fall into your lap via housing lottery.