We spent an entire morning at the Museum of Natural History, and we personally chose to visit because it has the best and most extensive collection of dinosaur bones in the world. It opens at 10 am and admission is about $20. The main entrance has a huge dinosaur skeleton that greets visitors. I recommend that you go directly to the dinosaur floor because the museum is quiet and and you be nearly alone. The T-Rex surprised me the most, and is made almost exclusively from bones of two specimens found in Montana. It is the same T-Rex from the movie "Night at the Museum." I also enjoyed the dioramas, where the largest meteorite in the museum collection is preserved.