Book 2 nights in Abu Dhabi and get free entry to Louvre, Zayed National Museum & Natural History Museum

Saw this on Khaleej Times, they also mention that it can be combined with the “Kids Go Free” offer at select hotels, allowing one child under the age of 12 to receive complimentary stay, meals and access to attractions when accompanied by a paying adult.

But in short, if you book 2 nights at any of 171 hotels in Abu Dhabi, they give you free entry to the Louvre, Zayed National Museum, and the Natural History Museum. It's honestly not very clear which hotels are part of that 171, so better check with them directly prior to booking. You just need to collect your passes at your hotel while checking in. 

Not bad for a family or weekend trip.