I've owned 28mm and 35mm fixed focal length lenses in the past and now prefer to have a zoom that covers those focal lengths. The less time I spend changing lenses the less chance there is of missing photographs, and most zooms these days--even the inexpensive ones--give great image quality if stopped down to 5.6 or so.
That said, if you're photographing indoors without a flash an f/2.8 or faster aperture is nice, until you factor in very short depth of field which, when photographing groups of people, can mean that someone who is half a step back from the person in the group the camera focuses on can wind up slightly out of focus. That's where using a flash comes in handy. A good flash, bounced off the ceiling to avoid harsh shadows, can give you enough light to stop down to 5.6 or 8 and get the depth of field you'll need.
