For a natural light photographer, indoor weddings are the best way to showcase how good they are, using the available light to create beautiful photographs without under-exposing the images.
I am a destination wedding photographer, so even if where I am based at (California) majority of the couples choose to get married outdoor, I always happen to photograph an indoor wedding, whether is the ceremony in a church or the reception in a banquet hall, or a full day in a theatre (take a look at this stunning wedding at The Orpheum Theatre).
Indoor weddings can be very challenging and my best advice to you, dear fellow photographer, is to gear up with wide aperture lenses. I stay away from speed lights because I don't like the artificial look that they give but I support the lack of natural light, if necessary, with my Fiilex lights (take a look at the video).
Here you can see an example of a fully indoor wedding photographed only with the use of great lenses (F 1.2) and Fiilex lights.