For these shorts, I modified an Ottobre sweatpants pattern which looks like yoga pants. I like the wide waistband. The Ottobre instructions have you attach a piece of clear elastic down the center of the knit waistband. I tried that technique once (in boys' sweatpants) and, let me tell you, it's wretched. Clear elastic is not strong enough, nor does all that waistband look nice gathered with such a narrow piece of elastic.
So I used 2" wide waistband elastic for a yoga waistband look. Sara didn't like how tight the waistband was in the first (light gray) pair. That wide elastic is so strong, you can't go with the same negative ease you would with 3/4" elastic.
So for the second pair, I cut the elastic to the same size her waist was (at the waistband location) AND altered both the waistband and the pants so they were both the same measurement as the elastic. That meant lengthening the waistband piece and reducing the width of the pants at the side seams. Now the top of the pants don't have to be gathered to the waistband and it's possible to get a smooth waistband. If you're interested, Ikat Bag did a tutorial for the Smooth Waistband.
I like these shorts and they're very simple to whip up. I'm sure I'll make a few more colors, but that may have to wait until after our trip.
Here's a photo of the wide elastic, available at Cleaner's Supply.
Pattern: Jump Sweatpants (Ottobre 1-2008-19).