I'm going back to Apulia the month after your visit. You can tell what I think of the holiday in that it's my first repeat holiday (ever).
Ostuni was a really interesting place, There's plenty to see and do there. On our visit in 2011, we managed to have an alfresco coffee, visited a fascinating church, did some shopping (I bought some great glassware), and had an alfresco lunch. Very nice!!
I'm sure you will love it. Evereyone's so friendly on a JY holiday!