That looks like a pretty difficult task, as it is not easy to relate Bitcoin to "tangible" things mostly shown in museums. But it may work. Good luck
![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)
Take advantage from the fact that you'll have more space dedicated to Bitcoin than most people - most see explanations and infographics on small screens, with luck on a big TV. I would propose a big screen covering one whole wall, where you could show difficult-to-grasp ideas in animations, like the way mining and the blockchain work, and even things like an 51% attack (where one chain replaces another). You could even include a kind of blockchain game, to show the general principles of Proof of Work. That could be realized as a card game which you could sell at the museum.
And yes, a big (and expanding) timeline, photos of the first Pizza bought with Bitcoin, Casascius Coins, photos of a mining farm in China, etc.