To drive to Petit Jean State Park, Take Hwy 9 (Exit 108) off I-40 at Morrilton south 9 miles to Oppelo. Then head west 12 miles on Hwy 154 to the park; OR, take Hwy 7 off I-40 (south), OR, off I-30 (north) to Centerville, then east 16 miles on Hwy 154 to the park; OR, take Hwy 155 from Hwy 10 at Casa.
To get to Cedar Falls, follow the trail from Mather Lodge. It is 2 miles roundtrip, with a pretty severe elevation change that really flexes it's muscles when you're hiking out. The springtime is the best all over Petit Jean Mountain. From late March until early June, you'll see many wildflower species many tree species in bloom. April is my favorite month here when the redbuds and dogwoods are ablaze. The summer is hot and seldom has much water flow. The fall can be an amazing time if there have been any good rains. You generally avoid the crowds by going early in the morning, and the light is great when the sun is low in the sky. Late afternoon can provide amazing light, too, from time to time.