I am not finding a land and island tour by Rick Steve’s. Do they offer one? I’m looking for maybe 7 or so days in Athens, Delphi, Olympia and maybe 5-7 days at Mykonos and santorini.
The 14 days in the Heart of Greece tour includes two nights on Hydra, which is an island. Not the mix you're looking for, though.
We did the 14 day RS Greece tour last year and it was spectacular. It covers the Peleponnese peninsula and the island of Hydra. After the tour, we spent 4 nights each in Mykonos and Santorini which we planned on our own. It’s fairly easy to plan on your own.