The north is very Mediterranean in feel, and a lot like Southern France if you've ever been there. Sidi Bou Said was amazing, and there were very few people at Carthage when I went, and zero people at the amazing American WWII cemetery nearby, except for the American guards (the only Americans I ran into in 2 weeks).

The middle part of the country is Arab, complete with Arab fortifications. I went to a castle (Sfax?) that looked like a rook piece from a chess set. The souks were great. The Roman amphitheater at El Jem was really cool, too. I think they used it for Gladiator.

In the southern part you enter the Sahara and the Berber culture. The old fortified villages, the ksours, blew my mind. Like something from a fantasy novel. I definitely recommend a trek for a few days into the Sahara on camel. I saw neolithic paintings of hippos and other long gone animals, and sleeping under the stars with the thin air and zero light pollution was incredible.

Everyone spoke French. I'm not sure how well they speak English, though, since I took it as an opportunity to speak French. Wish I'd had some Arabic other than a handful of words I picked up travelling. Almost all the tourists were Italian or French. I was there in early November. Warm days, chilly nights.