Even though our processor is 1Ghz, I've found that 550 or so mHz (yours could be different) works just fine for everything I run. If you're on one of the newest sense gb roms you will only have 3 governors, on-demand, performance, and user-space. On-demand is default and is ok. Stay away from performance if you like your battery. Userspace is used by applications i believe, but not relevant anyway. If your on an AOSP ROM you should see more depending on your kernel; powersave, smartass, and conservative. For me smartass works the best, but you could be different. As far as profiles go, it's up to you. The lower the speeds the better the battery life. While charging you could always go a little faster because you're not on the battery. Screen off=low speed. If you're not using it, don't let the processor use it.
It really depends on the ROM, kernel, and your habits.
Good luck!