I recently bought the Little Comet Tails Crescent Moon Yoga Pants pattern and I love it! I have grand plans to make some flongies & florties (fleece longies & shorties) for the two younger ones, but it also fits Emma, who is nearly 6 and big for her age. Of course the length is way off ;) but that's easy to extend, and this pair I wanted to be about knee length for summer anyway:
They fit really well and Emma thinks they're comfy, which is a big deal as she's very fussy about what she'll wear.
My two little helpers helping me ice Emma's birthday cake (her birthday isn't until Thursday, but we celebrated with the family on Sunday because my FIL works 1-day fortnights and that was his day off):