Typical Chinese traveling

Come like winds, go like winds.

In my humble opinion, most national parks deserve at least 3 days of visiting to experience their beauty in different ways.

Day 1 : watch movie/video at visitor  center, get to know parks' history,  geology , climate and the impacts on todays vegetation and animals, to see the parks'natural beauty  in all seasons. Participate a rangers program or a guided tour,   ask questions and listen  to his/her explanations.  Also, pick up trail maps for later use. 

Day 2 : drive around to see all interest points of the park, take pictures.   

Day 3, hike at least 1 or 2 famous trails in the park. Or do other activities  accordingly 

Same way when visiting some special  towns. Such as Moab,  "the holy city of mecca in mountain biking world", there are many world class mtb trails,  many  bike shops, best biking culture  and many other outdoor activities. Rent a bike, ride some trails, have a 4 wheeler tour.  Virgin,  another small town just outside Zion's west entrance, is the site  that  Red Bull Rampage MTB held annually. Though everyone can watch the contest videos online, it is more impressing and awe inspiring when you  see  those LINES ON CLIFF in person.