How about uncapping stores and town hall? After "maxing the town" you need to push town hall further to obtain new possibilities. Also after current max level there will be no more new items in stores, but after finishing next lvl, few items will be randomly selected and exchanged for something else. And the idea to make city more beautiful is good ... This way it will not give unfair advantages over younger cities. Maybe with raising town hall you can get a prefix for your town name like City, City state, ...