I just did a quick check for July 12-14, and for three days regular Express for 2 people it was $560.
Cabana Bay rack rate for those dates was $169 per night, $507 total, so with the pass that would be $1067.
Royal Pacific rack rate was $329 per night, so for three nights that's $987.
Now obviously you might be getting better deals on the hotels than the rack rate, but it definitely seems like you'd save money by going Royal Pacific, and although Cabana is great Royal Pacific is a step above, so definitely worth it if Express is important.
The main factor that changes the math is if you decided just to have one day of Express and use regular lines for the remainder of the trip, as then Cabana comes out cheaper.