Yeah, I've spent a LOT of time on the Cape. It's a GREAT place. Get's pretty crowded in the summer, but there is miles and MILES of beach. VERY laid back between Labor Day and Memorial Day. All kinds of great fishing. Housing is DAMN expensive. It's fairly large so where you work will help decide where to live. Do some exploring...quaint little well preserved towns (Chatham, Truro, Provincetown, etc.). Hyannis is more modern/generic/blah.
A couple of "must do's":
Go on a whale watch tour
trip to the islands (Martha's Vineyard, Nantucket)
Weekend in Beantown (can take a ferry from P-town)
Red Sox vs. Yankees at Fenway Park (avoid the bleachers. Best seats are above the "Green Monster")
Fall foliage trip to New Hampshire, Vermont, and/or Maine, in Mid- October. Get up in the Mountains.
Plymouth Plantation
4th of July Boston Pops concert/fireworks on the Esplanade (Charles River).
I could go on and on.....ENJOY! Oh yeah, get some warm clothes!