Trying to buy some concert tickets on craiglist and I noticed there are several different colors of parking pass... which ones are closest to the stadium and which are furthest? And I'm guessing they're all different prices?
I wouldn't recommend rodeo parking. You will be waiting in your car for almost an hour to leave and maybe get in. park downtown or behind Sams near NRG (Metro park and ride) and take the rail instead.
Another option, which is what we did last year, is to park somewhere off of the metro rail by the museum district and ride the train to/from. You still may be stuck in some long waits and packed metro rail cars on the way out but its much better than being stuck in traffic for an hour like REEKO said.
Metro Park and ride is also a good option. There's a park and ride location on OST that's a short ride to and from NRG on a bus. Like other posters have mentioned you may have to wait a little in line for the ride back on the bus at the end of the night but you'll be dropped off and picked up right at the front of the carnival / show grounds: http://www.rodeohouston.com/GuestServices/Transportation/ParkRide.aspx
or dont go. Buy a live hits album and a Bose system, bottle of wine, invite your girl and you're set.
Heard that if you come on Horseback to the Rodeo they let you park your horse right at the front gate for free.