Poohsfan 1 - I was referring to the days you BOOK your flight, not the day you actually fly.
Fares fluctuate during the week; at least on Airtran. It just seemed like starting on Fridays and ending on Mondays, the same flight was higher, because families are probably all together and planning at the same time when to go, what to do, etc.
During the week, the fares would go down, and when I booked mine - between 6:30 am and the time my friends booked at noon, it had actually gone up about $30.00.