In a lot of ways, shopping at Costco feels like cheating the system — you can save money on gas, get good deals on auto insurance, and, of course, snag a $5 rotisserie chicken all in one swoop. But, houseoutlook.com says it’s possible you’re not using your Costco membership to its fullest potential, even if you’re a seasoned shopper.

Michigan is chock full of water, where lakes, rivers, ponds and streams abound. But perhaps the most enchanting waters are those that...