Sonic is great for a quick snack or a mid-afternoon drink. The kids love the slushes, and the tater tots are tasty. Don't actually eat the other food very often, but it doesn't seem any better or worse than the other fast-food burger places. They have a half-price happy hour for the drinks which the family likes to take advantage of. The Sonic near us, actually has picnic benches with umbrellas, so you could sit and eat if you want (although weather might prevent this).
No A&W near us, but we have a Stewart's. Similar to what people have said about A&W, Stewart's has great root beers and root beer floats. Food is so-so, which is to say, its about the same as any Friendly's or Denny's. It's a nice place that's been in the town for a long time, run by a local family.