[DiapDealer]

The phrase "serious readers" should really be retired (or at least renamed). Its use rarely seems to convey its intended meaning, and typically only angers those who get left off of the "serious" bus.

If we're talking volume, then I'd suggest "hardcore" or "heavy" readers (and conversely, "casual" or "lighter" readers). And if it's being used to talk about those who read what some might consider more highbrow or difficult, I'd suggest don't. The distinction is rarely helpful and almost never relevant.