You must visit the MAG centre, were you can find out everything about the bombing in laos. They have a very nice tool in google maps, where you can see how bad it was.
There's only one good restaurant, that's called Coasters. It's next to the MAG centre I've stayed in 'Nice guesthouse' which was clean, cheap with friendly people.
You should visit the Plain of Jars nearby and the bombed temple in Muang Khoun. This is easily done by motorbike, which can be rented in Phonsavan. If you don't drive outside the city it's quite sad and silent. Don't worry about accomodation, you will be picked up at the busstation.
