What is the best wood for building a bookcase?

I would love to build my boyfriend a custom made bookcase for his birthday (witch is in 5 months), for him to display his statue collection, but my problem is that I don't know anything about building, materials, or where to begin for that matter. I have a friend that is very handy, and I'm planning on asking him to build it for me but I would like to sound like I know what I'm talking about before I go and ask him for that favor. I would appreciate if you can guide me in the right direction. The only thing I know is that I want the bookcase to be about 6.5ft X 4in. I believe that is more than enough space for him to display his collectibles.