Less than a mile to Phila Museum of Art from 30th Street. However, the other museums are closer to Suburban Station - about a half a mile. Check Google maps for the Ben Franklin Parkway (museum row).
It's a nice walk to the museum. Take JFK Blvd. towards west. Take the steps down to Schuylkill River Trail and towards PMA. Make sure to walk on the right side of the trail and do not block the trail while walking when you are in a group of three or more. Fast moving biker will not like you.
Thanks! Your answer is awaiting moderation.