I'm not sure if you can have lasers or technology without some cities. You'd need at least some form of manufacturing base for any technology beyond revolvers and lever action rifles. Maybe some small "cities" of a few thousands of people? Or perhaps all the technology from before is all that there is left and there is no making more? Then you could treat them almost like magical items. Thus, instead of cities you could have "Barter Town" like from Mad Max's Thunderdome. (Chant with me now... Two men enter. One man leaves!)