Bus tours!

As for almost every large tourist destination in the US, you can find here tons of bus tours. My favorite are the ones where you pay for a pass and can hop on or off as often as you'd like during the valid period of your pass. That way, not only do you benefit from the bus tour but it serves you as transport to get around the city as well. The bus company will provide you with a schedule and list of stops and they usually pass by pretty often. It is pretty convenient and will save you on the cost of public transit or taxis.
Sit back and enjoy the ride!