they have chair there but it is 1st come 1st get. However they are all over the place, some in shady (as in less sun, not the other type of shady lol) parts of the park.
We like to rent an "Umbrella" which is in a secluded area (not private) and it has 2 lounge chairs, 2 regular chairs, small side table and an umbrella. Its nice b/c its reserved and secluded enough you can keep your stuff slightly more safely. Its around $50 for the day.
If you really want private and safe, you can rent a cabana. they are different based on the parks, but you get a private area with a locker, fridge, towels (I believe) and an attendant to get you anything you need. Those are a few hundred $$ but worth it to some.