2gypsies wrote:
3-4 days would be ideal for you. Here's the park's web site which gives 'Things To Do' and lots of other great information. Explore it.
Grand Canyon Nat'l Park
By the way, each national park has a site like this to give you lots of ideas.
Plan to stay IN the park for the best experience and take some ranger programs. May should be ideal in terms of weather and crowds.
One particular thing I'd advise is to hike down the Bright Angel Trail if only for 1/8 to 1/2 miles. You'll get the real feeling of the Canyon rather than just staying on the top.
Also, hiking different parts of the Rim Trail is great. It's a place where you might find some solitude away from the crowds to take it all in. Ride the free shuttle and get off and on at different parts of the trail.
Some folks will recommend staying in Williams and taking the train. You should know that you will only have a couple hours at the Canyon itself and the scenery from Williams to the Canyon is flat sagebrush.
Some folks don't seem to appreciate our awesome national parks and they just want a peek to say that they were there. Exploring the park fully will give you a whole new perspective and appreciation as to why these are national parks.
You stated you're planning 6 days at Zion. If you're not hikers then I'd cut this down to 3 or 4 days, also. Zion is a hiking park.
How much time do you have for this whole trip?
Remember, there are other great national parks in this area: Bryce, Capitol Reef. Arches, Canyonlands and a non-nat'l park, Monument Valley. All are worth visiting. Each one is completely different and because of distances, staying in or near each one is advised.
6 days in Zion will also cover Bryce. We do enjoy hiking and plan on it in Zion The hikes in GC all seemed to be steep and strenuous. Our total time for this trip 14-17 days. after Zion and Bryce we plan on 1-2 days in Great Basin NP.