Jonathan Pryce is well known among theatre people, and perhaps to the British, but Americans will recognizing him vaguely as "that one guy in Pirates of the Carribean" or "That guy from the Lexus Commercials". I'm certainly a fan of his (I think he's a better *musical* actor... and Brazil is one o my favorites), but the average tourist is probably more familiar with Lithgow. "Oh, we like that show with the aliens..."
Norbert might be a minor draw from some of the TV appearances. Ms. Rene Scott, though talaented, is not a draw outside of theatre people, and frankly, many NY actresses could do her role as well or better.
I'd wager that, for morst tourists, Scoundrels is a shaky fourth on the list of things to see (unless you have kids, which bumps it off completely). However, I think it's nearly the best thing on Broadway, and has already had a respectable run, and I certainly hope for longer.