At the Foot of Denali
Wonder Lake Campground is at mile 85 on the Denali Park Road. It offers 28 sites, which are all tent-only. It is open June 8 - mid-September each year.
It is the closest campground to Denali. Though due south of the campground by nearly 26 miles, the sheer size of "the mountain" makes it loom impressively over the area. Cloudy skies can obscure views, and mosquitoes can be fierce, but Wonder Lake on a clear day offers views that will last a lifetime.
Vehicle access to Wonder Lake is only by camper bus.
You may make reservations online, through a third-party reservation system. Reservations are possible as early as December 1 of the summer before you wish to visit (e.g., Dec 1, 2015 for a 2016 visit). Reservations at Wonder Lake are strongly recommended - it is a very popular campground!