I know a lot of people are into carrying backpacks to the parks, and I used to be one of them... but I no longer feel like I have to have every little thing with me. If you have kids and need to pack snacks and diapers or other necessities it probably still makes sense, especially if you don't have a stroller with you, but I think most people will be perfectly fine with a good quality cross-body bag.
LeSportSac bags are also super easy to clean and very durable. Similarly, Vera Bradley bags are worth every penny as well and you can get similar deals on them (its def worth following both brands through email and through Facebook to get up to date sale and clearance info).
What is so nice about the Vera bag is the comfort level since they are softer cotton and even when you weight your bag down (which, lets face it, we all do sometimes while touring) it never cuts into your shoulder. I especially love that I can put my Sony Nex camera in my Vera and feel like it is still protected! Its a compact DSLR and I keep the zoom lens on nearly all the time! Like the LeSportSac bags, you can through these in the washer when you get home if they get dirty and getting wet won't kill them. They also have lots of pockets!
And one of my go tos for my my bags is being able to hook a Mickey shaped caribeener I picked up a few trips ago onto the strap so I can hook my refill mug on-- and both of these are soft enough or have small enough straps that they fit no problem!
What is your favorite park bag? Have you ever rocked a cross-body? I think they are cute, stylish, and an easy park choice!