It all depends on the type of image of your company is trying to project (and your budget). A decent dinner, perhaps in a private dining room with a girleen bashing out some low key trad on a harp, would show you as sophisticated but with an Irish touch. Make a few calls to hotels near you and ask what they can provide/organize. If the big wigs want to go to the pub, make it their suggestion, i.e. ask if they want to go but don't drag them out. You don't want to give the impression you are booze heads. Also, make sure your own staff don't get blotto; remind them they are on business during the dinner and must give a good impression.