Nature Moms just posted a wonderful review of BPA free sippy cup options!
Gabi is beyond sippy cups now, but we are eliminating plastics from our home, including water bottles, and I'm always on the look out for alternative ways to carry water. We currently have Klean Kanteen water bottles, made of stainless steal, but I just discovered they are made in China. I don't doubt that they are safe, I'm just trying to avoid supporting the Chinese government in any way (it's hard!!). We'll keep the ones we have, but won't be buying any more.
Most of the companies listed in Nature Mom's post also have cup options for older children. I think we'll try a Sigg! Gabi will have a blast picking out her favorite design.