You can easily see a sampling of the highlights on the Cape and islands in a week, and you'll still have many hours for lounging around on the beach, a don't-miss activity. Two weeks will enable you to see all the most interesting attractions in the region plus have even more time to spend with your family. It's best to plan a leisurely visit that allows plenty of opportunities to try a different beach every day, to poke around antiques shops, or to explore marshes by kayak.
Cape Cod does not have a very convenient public transportation system, so you will have to drive your own car to see the sites. Take traffic into account when planning your itineraries. Getting an early start on the road is critical if you are staying in Falmouth, say, and want to drive to the Outer Cape to check out the Cape Cod National Seashore. Avoid midday drives on roads such as Route 28 from Falmouth to Dennis; it tends to be loaded with traffic.
Both Martha's Vineyard and Nantucket have excellent public transportation systems, and when you visit the islands you can leave your car behind. On both islands, and occasionally on Cape Cod, you can explore on bicycle; I'll include the must-ride bike paths.
Staying in a central area on the Cape is a good strategy for exploring the peninsula. Spending a couple of nights in Provincetown or on the islands of Nantucket and Martha's Vineyard is also a real treat.
There are 15 towns on Cape Cod, six towns on Martha's Vineyard, and one main town on Nantucket. The itineraries below do not include visits to every town, but you may find yourself stopping between recommended attractions for, say, refreshment at a quaint ice-cream parlor. The Cape is full of discoveries for those who wander off the beaten track.
No matter which itinerary you choose, you'll want to include some unstructured time on the beach or at one of the Cape's many freshwater ponds, because enjoying the outdoors is really what the Cape is all about.