I really love Bridal Veil Falls. This is another really simple, easy (quarter of a mile) waterfall hike (more like a stroll). You can play in the shallow water at the base of the falls, or, if you're more adventurous, climb right up the waterfall itself.
From I-15, take Exit 273 for 800 North in Orem, which becomes US Highway 189. About 4 miles up the canyon past the interchange, just past Canyon Glen Park, take the Nunn's Park exit, and park in the Bridal Veil Falls / Nunns Park parking lot (on the right side of the road).
Have a picnic in the park, then follow the paved path straight up to the falls.
Free. Info here