Since we spend most of our time and travels boondocking (no hookups), when we actually plug in at a campground, it's considered a luxury. Campgrounds are a great option if you need a night or two to charge batteries, fill water and dump sewer tanks. They're also almost always pricey. We've stayed at about a dozen campgrounds across the country, and still prefer boondocking (or roughin' it), however it's nice to have a true "mobile home" every now and then.
Campgrounds vary substantially from one to the next; sometimes we've got room to spread out our slides and relax, others we're barely fitting into the space. It pays to do your research and call ahead of time as much as possible to ensure your RV will fit, and also get to know the staff via phone. Though we'd much rather boondock (bonus: no neighbors), plugging in at a campground every now and again gives us a chance to regroup and experience the city a little more - without having to worry about our bus.