I was there last week on Thursday. Had a great day, doing the following:
get there early. I arrived in the entrance queue around 730 and that was probably pushing my luck, since the queue moves miserably slowly and I only got in the park around 930. That was still early enough to load the app and get a standby pass for peter pan, a priority pass for whatever you want, and a premier pass for journey (all other fantasy springs passes where sold out already). after an hour or so you can get more premier passes, so I got one for tower (could have done soaring or toy story, but meh). They seem to release batches of premier passes randomly on the half-hour, so I kept checking throughout the day but eventually at 2:30 I noticed there were a bunch more fantasy springs ones on offer, so I just sat down and repeatedly refreshed the app until I actually got a frozen one I could buy---took about five minutes of refreshing.
So ultimately I didn't end up waiting in any standby lines for the big attractions (other than the transit steamer/sinbad, etc) and used priority+premier passes to never wait more than about 20 minutes all day. I only got the two (considered the better) FP rides---I actually never saw tangled premier passes come up for sale again. Personally I'd rank peter pan extremely high and frozen decently high. I just think the former is almost a perfect 'fantasyland' dark ride, with excellent theming and just a huge fun factor. Frozen is certainly beautiful and good but as a cohesive dark ride I found it a little more boring. Still worth the effort though
This seems like such a miserable way for a theme park to operate. I know Universal Osaka is similar having recently been, though nowhere near as bad as it's at least only Nintendo World that has this (plus you can either book in advance or generally get access later in the day unless it's especially busy).
Is there any way to visit DisneySea and not spend your day glued to a phone trying to get slots and arriving at absurdly early hours? Can you buy advance fast passes that cover most things?