ADRs ARE A MUST!!!!!!
I am pretty sure the time of just walking up to a resturant that you want to eat at in WDW is gone. With any of the Dining Plans in place, you HAD to have ADRs. We had the Silver Plan, (years ago!) and we were surprised at the number, back then, that were turned away from different resturants and this was when Easter and Spring Break were in April. It may not be crowded in the parks during "off season", (is there really such a thing anymore?), but the resturants are packed, it seems.