We always bring our bikes! We are not bus transportation type people and I don't like spending $30 a day for a golf cart, so to make getting around the campground itself easier we always bring our bikes.
The campground itself is huge and the chances that you are right next to everything you want to do or need (i.e the pool, the grocery/merchandise store, the playground, the campfire program area, etc.)is very slim. Don't get me wrong you can certainly walk to wherever you need or want to go, but it WILL be a pretty good hike and I don't reccomnded doing that to anyone who is out of shape. You could also walk to the end of your loop area and catch the bus, but again we don't care for them as we are spoiled and always have our own car. Rest assured that each area has a place to lock up your bikes, but the campground seems to have pretty decent folks there and so we don't always lock up our bikes, not even at our own site.
Have fun and enjoy...