I think your best bet is probably the two Starbucks locations in the parks, but I scrolled through my photos from the last few trips and didn't see any bagels (they had other pastries, but not bagels that I could see, but it might be something they only carry in the mornings (I'm usually there in the afternoon/evening)). The Starbucks in DTD would probably have bagels (the one closest to the parks is a regular/full-sized Starbucks). Also, bagels are listed for a couple of the hotel locations (e.g., the Coffee House in DLH).