The right names are good for the promotion of a series. It might convince some people to check out the pilot on TV, who otherwise might just not care. But I think there aren't so many affordable actors out there, who will have a noticeable effect in this regard. For example Scott Bakula, when he was cast in ENT, was too unhip to be much of a special draw. Outside of big Hollywood actors, who they won't be able to get, the best names for promotion purposes are actors, who played very recently main characters in series, which got really many viewers. Michael Weatherly might have had an effect, but he is in another series now. House ended already a bit longer ago, but Hugh Laurie might still work this way. Most actors though are kind useless for promotion purposes. You might as well just get a cast of talented unknowns and produce a good series. Then people will watch it, no matter what actors are in it.
