In addition to what you've mentioned, I love Alan Menken's theme song for the Sindbad's Storybook Voyage at Tokyo DisneySea. Robert Moline's "Golden Dream" never fails to get me, too, and the entire soundtrack of Impressions de France remains an international treasure.
This article reminds me of a presentation I did in college about John Williams in a room of mostly non-musicians, and I played parts of different movie soundtracks for the students to identify which movie it was from. The idea was to show them how music plays an important role in making us remember situations and events, in this case a movie.
Yes, I think this is a mark of good sound design in a park. It's almost like being on an omnimover ride. The park itself is another E-ticket.
I also love Epcot's entry music, and of course, the JP theme in Islands of Adventure.
I think just the music in general around Epcot and Islands of Adventure is pretty darn good. It's funny because those are my two favorite parks.
Some of the best original theme park music I've heard typically comes from shows, perhpas because it's more noticeable than background music in the parks. I'm always grabbed by the soundtrack to Sea World's Blue Horizons, and I've loved the old Electric Light Parade music and remember listening to it on vinyl back in the day.
I do enjoy the Fantasmic! music, and find myself humming it for hours after the show ends much like I used to do following the original Illuminations soundtrack, not so much with the newer Illuminations music though.
The music in the front square of Epcot's Future World is brings a lot of the optimistic modernism that defines the park.
Top Thrill Dragster using the 90's Brit Pop song Ready to Go to pump ump riders in the station.
Check out Roller Coaster Tycoon 2 soundtrack for some great amusement park themes.