I read the other posts. The REAL Cape is Wellfleet, Truro, P-Town.Less people more enviorment. Marconi Beach is a great stop. Falmouth is strip malls, motels and crowds.Like West Yarmouth. You can get a ferry in Hyannis to the Islands but I wuldn't recommend Hyannis.
If you want to see Blue Man or another show you can get half price tickets at BosTix located at Quincy Market or Copley Square. www.artsboston.com or org. The seats weren't bad for Blue Man and you'll pay $25 instead of $50. The theater holds about 500 maybe.
Make sure you do a harbor cruise to Georges Island $8. www.bostonharborcruises.com.
Better yet get the entertainment book, only $10 right now. www.entertainment.com