I think the universal premium hotels are worth it for the unlimited express.
I don’t think you priced it properly if you think cabana plus unlimited express for 9 people is cheaper than premium hotels. (Unless you are spending most of your stay away from universal studios and IOA. )
Unlimited express is highly underrated if you want to do things more than once and are going to be in US and IOA a bunch. Our family once rode Popeye 12 times in a row, for example. 75 minutes of hilarious stupidity we will never forget, and great fun being 100% soaked, and watching people get on in nice clothes and heels and stuff, only realizing they are screwed once they look at us and the ride has started. I believe the line was about 20 minutes, but with on site express it was a walk-on each time.
It depends on what you value more and my group likes to ride, ride, ride, and max out the attractions. If we were spending more than one day OUTSIDE of US and IOA, it does start to be a waste of money. But we spend all our time in the parks and city walk.