Patricia:
Like you, I don't have the typical 1.8 children either, and sometimes that's tough when Disney's Value Resort rooms max out at four to a room!
For a family of 5, your most economical choice is
Port Orleans: Riverside. It is the only Value or Moderate resort that accommodates five without upgrading to a suite. Its trundle bed allows you to sleep a youngster over the age of 2 in your room. (And I do mean youngster, as the trundle mattress is not a typical 6-inch-thick mattress on trundle springs. It's more like a thick mat on a roll-away slide.)
When our family stayed at POR, our favorite amenity besides the cool pool and slide was the boat to Downtown Disney! Our kids saw the boat as another attraction! Coupled with the lush landscaping, POR felt more like a Deluxe resort than any of the other Values or Moderates I'd stayed at.
As for the crowds in August, keep in mind that attendance tends to follow the pattern of school enrollment....there will still be crowds the first week of August as Northern schools typically go back in session later than their Southern counterparts, but by mid-August the parks thin out. My advice: go as late in August as your school schedule allows. Value rates begin August 9, and if you can swing it, Disney offers free dining for stays beginning August 16 when you purchase a room with park tickets! (This offer is a good indication that even Disney thinks August crowds can be low!)
If you've got any more questions or need followup on Port Orleans, just contact me through my bio page!
Wishing you a magical vacation!
Whitney