Unless you are specifically going for the kind of grain that higher ISO may give (and you don't want to use a software grain-engine in post-processing), I second zackiedawgs advice.
Regardless of the drastic improvements over the last few years, in high-ISO noise control, the premise remains the same. You are electronically amplifying a signal - much like turning up the volume on a stereo system. It's an electronic adjustment that has nothing to do with the path of the light.
The trick is to be conscious about it - For example: if you have F8 at 1/60sec at ISO 800, F11 at 1/60sec require ISO 1600. Conversely, to achieve 1/120 sec at F8 will require ISO1600.
Here's what I do - I tell my auto-ISO that I want to use minimum ISO200 and max ISO1600 and then I set a minimum shutter speed @ 1/30sec (which is about the slowest I can handhold a 35mm lens on a DX camera without stabilization) and then I use shutter or aperture priority as desired. With a different lens, I may change the minimum shutter speed accordingly.
If we are talking human subjects moving "normally" (i.e not all-out sports, but goofing around and even dancing - except if it's heavy metal or dubstep..hehe) the required shutter speed is 1/250sec to freeze motion (give and take 25%). For athletic endeavors and running dogs, it it more 1/sec.
if you have such thumb-rules in mind and make your preferred settings accordingly, you can ensure that you achieve lowest possible ISO under a range or circumstances.