If they're going to do a clean-sheet design then I think we'd all have some suggestions. Large solar panels would greatly extend surface missions, and the capability to have a crew of more than two would be nice (can you imagine what a millionaire would pay to walk ON THE MOON?!) as would a slightly more comfortable sleeping area. And in lunar gravity they can eat normal food, cooked normally, so a little stove (powered by the solar panels) where they could flip an egg in 1/6th G would probably be the most-watched egg flip in the history of live television.
Another thing I think we would all agree on is a better moon-buggy, perhaps with both fuel cells and solar/batteries so that it doubles as a tele-operated rover after the astronauts leave. Perhaps the greatest omission of Apollo was putting something as big and robust as the moon buggies on the moon, fully equiped with cameras and high speed uplinks, and not
having each of them creep around for a few more years, covering hundreds of times more area than the astronauts reached.