I see the "city" as a place with businesses and parking on the side. I'm a fan of any scooter except, perhaps, a 50cc. At that point I prefer a bicycle.
My two cents; if you will be in a lot of stop and go, stay small. Never above 50mph? Try a 150cc. Never above 70mph? Try a 2500-250cc. Plan on doing it all including riding with a group to a place some miles away? In this scenario you are looking for the "overkill" bike. I have had many scoots including an Aprilia Scarabeo 500. This thing had power beyond its ability which made it fun. I also was able to get 63mpg all day and twist up to a true 110 mph. But at the end of the day I wished I had bought the Aprilia Sportcity 250 or the Piaggio BV 250.