Places of Interest in Yazd
Yazd
Yazd, one of the oldest inhabited places on earth. The old city looks it too, although it's in much better repair than the old city in Bushehr.
Old information follows, to be updated some time soon.
The Amir Chaqmagh Hostel is a decent place to stay, at 80,000 for a three bed room.
As far as sites go, the LP walking tour isn't a bad way to go. The old city, in my opinion, is the biggest draw, with small winding lanes between mud walls running everywhere. The other sites are not so flash, although there are some very impressive minarets around.
The Barg-e Doulat Abad should be visited only to make a point, as they still cling to huge double pricing. Irani visitors are charged 3,000 - you will be charged 30,000. Go, demand local price and make an arse of yourself when they refuse you. Feel free to abuse the guy trying to charge you, he can issue you a local priced ticket if he feels like it. If they don't get the abuse, they won't change their ways. Think of it as correcting a wayward child.
There are also a few out of town sites to visit, including the Zoroastrian Towers of Silence nearby the town, and the town of Kharanaq. Most tours also take in Meybod and Chak Chak, both of which are reasonably missable in my opinion, although if you aren't going to be seeing so much of Iran it's probably worth taking them in as well.