By far the easiest, most stress-free, way for visitors to explore the Zion Canyon floor during the main season is on the free shuttle. If you're staying in Springdale you can even leave your car at your hotel or B&B, take the town shuttle to the front gate, enter the park on foot, and catch the shuttle at the Visitor Center.
Take the shuttle to the top of Scenic Drive and you get off at the Temple of Sinewava stop (from which many visitors opt to take a hike along the relatively flat and very scenic Riverside Walk.) And, of course, visitors can choose to get on and off the shuttle at any of the seven other stops along the shuttle's route. But, to maximize the exploring experience, visitors can combine the shuttle with a bike. (Bring your own or rent one of the Green Bikes available at the Zion Lodge.)
As mentioned in my Week 2 A-i-R blog post, the National Park Service arranged a Green Bike for my use and I frequently loaded the bike on the shuttle's rack for the ride to the top of the Canyon. From there I could return down canyon (frequently letting gravity do most of the work as I coasted downhill) and stop as often as a new subject came into view.
The Green Bikes are even equipped with wire baskets that were the perfect size for my plein air sketch kits, water bottles, and tripod. And, while the Park Service had very generously provided me with a "white pass" that allowed me vehicular access to the entire length of Scenic Drive (during the high season, visitors staying at the Zion Lodge receive "red passes" that allow them to drive approximately half way up the canyon; day visitors, campers, and those staying in town may only drive their vehicles as far as Canyon Junction) I found that, on a bike, I could stop anywhere a scene offered itself (rather than just at designated parking spots and turn-outs) and the bike even made an excellent platform from which to shoot video as I coasted down canyon.
The experience was so rewarding artistically that, this spring, I'm putting together a "studio on two wheels" for further testing (maybe even adding a bike trailer for the occasional two-wheeled, man-powered adventure.)
Stay tune for updates and further developments.