highchair/booster seats

Hi -- Just wondering if anyone out there can recommend a booster seat for traveling and/or to leave at Grandma's house. I am looking at the Saftey First fold-up booster seat, First Years 3-in-1 booster seat, and the First Years reclining 3-stage feeding seat. Any recommendations? I would like to find something that will work for a 6-month old and on...

thanks!
-Susan