I have been torturing myself over this and I've gotten nowhere for years :'( I know it was dark blue and possibly had a rollercoaster on the front cover? Not sure on the rollercoaster bit, but in my mind I see a sort of soaring scene on the front and something tells me it was a rollercoaster.
Definitely was a rectangular-shaped book, portrait orientation, hardcover, on the larger side. It had a set of cassette tapes that went along with it and was a combination of songs and story-telling - I believe it was about children on some kind of fun day or adventure. Definitely from (the latter half of) the 90s since that's when I received it and used it regularly.
It was not Disney affiliated or affiliated with any popular children's brand, characters, etc. It also was not affiliated with Kidsongs: Ride the Rollercoaster, which is what pops up most often when I try to Google this particular book.
Thank you!!