On my first trips to Maine, I’d hang a left at Cape Elizabeth and head into Casco Bay, usually tying up at DiMillo’s in downtown Portland and having a great dinner at one of the city’s many new, highly acclaimed restaurants. And then, most of the time, I’d have an early breakfast at Becky’s Diner, eating with the fishermen, before heading Down East to see friends in my favorite cruising grounds of Tenants Harbor or Somes Sound. Finally, I realized what a lot of people already knew. Casco Bay is a great cruising destination in itself, dotted with islands, beaches,…