What kind of tour are you looking at doing,bus,helicopter??We did the bus about 2 years ago and it was great and worth it but it's a lot of driving for the amount of time you spend at the canyon.You basically get picked up from your hotel around 7am,they take you to their offices where you pay and are given pastries for breakfast and then around 9 am leave.The bus takes almost 5 hours to get there,our bus driver stopped at a gift shop before we got to the south rim since souvenirs are cheaper there,here he also gave us our lunch which was basically a sandwich with cookies and chips.We got to the south rim at about 2pm where our bus stopped at 2 different places.We spent probably no more than 2 hours in total at the canyon and then headed back.
I have a family member who did the helicopter tour which is just a couple of hours as compared to the bus which was a whole day thing.We basically chose the company out of one of those Vegas magazines with the big ads that have like 12 different tours.Maybe someone could give you a good suggestion for a company.