Plan on spending at least an hour stuck in traffic when departing, unless you leave a good 30+minutes before the end. I would recommend arriving at least 1 hour before the show to avoid the inevitable cluster f*%k. The concert area has its own outdoor parking area (potential deep mud, hence the socks). It's a good walk to the casino parking lot but disable.
A poncho and spare socks+shoes are recommended, esp if you're parking there. Depending on you and the show it CAN be fun in the rain (ex. I recommend sunscreen as well as some other protection, such as a beach umbrella or parasol (sitting in the sun for over 2 hours in 90° weather is brutal!). For the summer concert series all the seating is open air.
