This is a bit late to be answering this question but here I go anyway. 1) I ALWAYS call in advance because IF there are any openings that day you want to eat there the spots are always gone 30 minutes after the park opens, so I would highly suggest calling in advance to make reservations. 2) The Blue Bayou is always crowded and popular, no matter what. When I went to DLR just last week the park was totally dead on Wednesday but the Blue Bayou was still packed, so make your reservations early if you can.
