I can't think of anything I want to see again in Shiraz. The surrounds were really interesting though, especially the ruins around Firuzabad (about 100 km south). About 10-20 km south of Shiraz, just before a 5km climb, there's a popular picnic spot where the locals invited me over for tea and snacks.
Can you travel independently as a Brit there these days? I thought it had changed since I was there (2011/12)