I've been wearing my pedometer to WDW for years. I record my daily milage and include it in my trip reports.
My daily average falls right in the 5-7 mile range, with Epcot naturally being a bit more at around 7-9 miles. My highest day on record, however, was 21.8 miles (April 22, 1999), and on that day I was AK, resort hopped to WL, and spent the evening at MGM.