In reply to Kramma:
If you're including the World, I'd recommend Cape Town and Surrounds, South Africa. There, you'll find long routes at all grades - lots or routes (and lots of absolute classics, too) around V. Diff..
If you run out in the town, there's the South of the Cape Peninsula and the nearby mountain passes or, about three to four hours drive will take you to many many more grand places. Expect multi-pich trad. between four and twelve pitches, at about 20 - 30 metres a pitch.
If you stay for a few weeks, your friend will be climbing harder just because the quality of the hard Sandstone rock, population of bomber placements and the friction (like bone-dry, 50 grit sandpaper) simply inspires confidence.
We don't do slimy and polished - a massive problem with easier grades on Limestone. What we do do is exposure. Bring your trad. undies. (South African for "pants")