No experience in OK but, tell us what you want to do. Fishing, boating, visiting relatives or friends????
There are a number of nice looking state park campgrounds within the confines of the Cherokee Nation tribal land, Cherokee Area at Grand Lake of the Cherokees on the Neosho river, just below the dam, Bernice area of Grand Lake State park, several different state and federal campgrounds on Tenkiller Ferry Lake, and a few others scattered around.
Just outside the tribal boundaries near the southern tip of the land is Lake Eufaula and the rather large Lake Eufaula State Park with three different campgounds. Arrowhead SP is just south of the town of Eufaula, near McAlester
The tribal land is about 120 mi N-S at its tallest point and about 80 mi E-W at its widest, and is almost 7,000 sq mi in size.
Charles