Pop Warner is usually not very visible except at the Value resorts (avoid the All-Stars and maybe Pop Century). As the week goes on we might see more of the kids in the parks as their teams get eliminated. I would avoid DHS on the day they have their party there, the 10th this year as I recall.
It is possible there will be less PW attendees this year because of the fuel and airfare costs, and fewer flights.
MouseFest should be no problem, just look at their schedule and go where they are not, but it's really not that many people.