Will you be going from Vegas?
You can drive, but there are car costs and hours of driving involved. It'll take away your whole day.
If you're willing to spend a bit extra, there are plane and helicopter tours. They pick you up from Vegas, show you amazing views of the canyon as well as Hoover Dam. Once you factor in the price of gas etc and time, I feel by air is best. That's what I'm doing on my next trip :) about 6 years ago