This is my third time to US. I choose to fly with Singapore airlines this time with 12 hours layover at Singapore. Did lot of Google search on what to do at Singapore during the transit time. As the entry into Singapore via transit Visa is free I decided to opt for it. But the airport has lot more to provide you than you actually going out. I did a free city tour provided buy the airport and rest of my time I spent roaming in the airport.