I agree that parking at the visitor center is tight, and I agree that 7th RV Ranch is a good place to stay for the visit.
I'm not going to sink into the Custer-versus-Indians banality, but for an informative historical view I highly recommend doing the guided tour at the battlefield. Our tour guide was a Crow Indian (who actually plays Crazy Horse in the annual reenactment) and he provided excellent commentary on the battle, what caused it, and the consequences of it, all in a way that was historically well-informed and that I felt honored both the Indians and the soldiers (including Custer). Well worth doing. FWIW, I also recommend reading Stephen Ambrose's Custer and Crazy Horse before the visit if you have time.
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