Dodecanese every time.
Start in Kos. Great big castle, and loads of ruins right in the heart of town. One or two nice restaurants. Elini's is my fav.
North to Pandeli on Leros. Hike up to castle, then sundowners at Cafe Del Mar, or move on to Archangelos for that deserted bay with lone taverna.
On to Patmos. St John's cave and the monastery.
Stop into Vlichadia on Kalymnos and check out the Sponge Divers Museum. Loads of things to look at (probably more fish
in the museum than in the sea) as well as a bunch of WW2 artefacts.
On to Nysiros. Do the Wild Bunch thing and rent a bunch of scooters from Mike at Eagles Nest. He will map you out bunch of things to see and do, including walking on the caldera of the volcano, take in the view from the cafe veranda in Emborios, and watch that perfect sunset at Mandraki (you can always grab a quick Monastery tour in as well).
Stop in to Tilos, and after dinner, grab the free bus at 2200 to the abandoned village. A dance floor like you've never seen before (unless you're a Burning Man kind of chap).
off to Alimye and anchor
off of the old German MTB base or moor stern to the remnants of the pier. Get the rugrats to gather firewood and BBQ on the beach or pier. Put out the fire PROPERLY before you head off to bed
Stop in to Panormitis and listen to the Monks sing Vespers. There's a little museum which features a load of ship models and votive offerings. Should hold the kids focus for a few minutes.
Symi town has a fab restaurant Muses, where you can freak your taste buds with really really realy slow cooked pork, carrot foam, ginger ice cream, and other molecular style fare.
Or.... some folk bypass Symi, hoist the Turkish flag and stop in to Knidos to explore the ruins, and hike to the lighthouse for that brilliant sunset view (the walk back in the dark is not for the faint-hearted).
Back to Kos and maybe a trip out to the original "Hospital" before heading to the airport
Along the way you'll see loads of other stuff that you'll want to come back to see.