Sophie, others on this forum will accuse me of being a Johnny-One-Note, but it can't be helped -- it's just that ONE island suits your needs and wants so perfectly ... NAXOS. Trip Advisor just issued its list of the World's 10 Best Islands, and the ONLY Greek Island that made the list -- in fact, the only island in whole Mediterranean area... was Naxos.. It's attractive to all ages -- grandparents, active 20s- 30s, teens, and young families. A few reasons why:
• 20 km of golden sandy beaches all in a row... some shallow, some deep, some even for "naturists"
• beautiful inland mountain landscapes & villages,
• tons of history: forts, ruins, a tiny FABULOUS museum, ancient statues, underwater ruins...
• fascinating port town winding maze-y lanes, shops, food markets -- and NO Mykonos Richy-Rich designer shops
• No package tourism - because airport doesn't take jumbo jets, harbor doesn't take giant cruise ships (YAY)
• Excellent bus system to reach all beaches, and hill villages, only rent car if you want a day of touring around
Here are some great pix of these hilights:
• Week in Naxos June 2014 - https://www.flickr.com/photos/stanbr54/sets/72157645113682278/
• Trip Around Naxos - http://www.flickr.com/photos/stanbr54/sets/72157634605629689/
• St. George Beach - https://www.flickr.com/photos/stanbr54/sets/72157632113170279/
• Naxos Town - https://www.flickr.com/photos/stanbr54/sets/72157632094558042/
St. George Beach is adjacent to Naxos Town, so it's an easy 10-minute stroll along the sea front to all the town shops, cafes, nightlife... yet beach-lodgings are quiet at night. This beach is shallow, but great for a dip, and a bus gets u to other beaches in 20 minutes. For a family, don't seek a "villa" (they are always way back from beach, need a car for everything). but instead book some adjoining "studio units" in nice budget lodgings with balconies right on the water, or just yards away. On St. George, Self-catering include: Studios Kalergis, Studios Thomais (upper floors of these), Hotel Naxia, Studios Naxos, Hotel Elizabeth. Beachfront Hotels includ Hotel Glaros, Hotel Asteria.
Daily 7:30 am ferry (modern large BLUE STAR, 1500 passengers) It's great to sit on deck & watch the wake, and if you pay about €5 more for "reserve airseat" there will e comfy leanback seats reserved when you go inside. It arrives about 12:45.... half a day. And if some in your party want to fly instead (45 minutes). there's 1 flight per day on a small (35 pp) MODERN jet. Sign up for Aegean Air "newsletter" (really an e-mail alert) and watch for "special" pricing; but don't wait too long these flights are fully booked months in advance... cost sabout €75?
There ... I've responded to your wish list. An island to please all 9 of you!