Summer vacation is starting to feel more like a luxury than a tradition for many American families.A new Deloitte survey found only 45% of Americans plan to take a summer vacation with a stay in paid lodging this year the lowest level in six years. Of those not traveling, 35% say they simply can't afford it.Smart shopping expert Trae Bodge, of TrueTrae.com, says rising costs are reshaping how people think about summer travel."We all love to get …