You just check in with security when you get there and they hand you a chair, and you go find a spot. You don't have to fight for a good spot or chairs.
If you get lawn tickets, the upgrade to VIP lawn is definitely worth it. We never stay under the pavilion in actual seats because it looks so crowded and hard to get in and out.
Great venue for concerts if you like the outdoors! Only complaint were food and drink prices, but that was expected.