It has been a couple of decades since I've been there and I've forgotten a lot of the details, but three things to see that immediately come to mind are the Gold Suq, the Tree of Life, and all the prehistoric graves just outside of town.
Also, when I was there the Holiday Inn (it was a really nice hotel) had "American night", which was a huge steak buffet and country music sung by a couple of Aussies. I remember an amazing Indian restaurant in town as well.
Edit to add: The country itself is really small. I think you can travel its length in under an hour. The sand is really fine and gets into everything, and from what I saw, beneath that thin layer of sand is stone. I liked the city of Manama. It was a typical big city, but its downtown was clean and well kept since it was a regional tourist hub.