Back to your original question...
Your scenario is a corner case for Disney.. and a scenario they do not address well. The needing 3 beds setup doesn't fit Disney's offerings.. so you end up buying multiple rooms or forced into these 'suites'. It sucks - but welcome to adulting
The alternative most try elsewhere first is to get a rollaway bed.. some may charge a small fee.. but cheaper than another room. Problem is usually they can not be guaranteed.
For families with more kids... they hit this often.. like my family with 3 kids. We just don't fit Disney's standard rooms.
This normally means you look to shop to find a product that has a 3rd bed (usually a pullout) like you found at Cabana Bay. So while it is a 'equal' comparison to your situation, it's not really an equal comparison for all...
For your dates...
For a single room Disney at AoA - Disney is charging avg $245/night before taxes.. or $191 if at ASM
Cabana Bay is charging $191 avg before taxes for a standard room
So when you look at baselines.. it's not really that much different. Parking is more expensive at UNI and it also 20+mins away.
You have the caveat tho for 'your situation' - the baselines don't work, and you fall into this rut where Disney doesn't have any attractive offerings, while Universal does with their room+sitting room setups. There, the Cabana Bay 'suite' is much more attractive compared to booking 2 rooms (~$35 upgrade vs $190 for an extra room).
Disney's 'family suites' at the values have always been priced almost as expensive as booking two rooms... and you were looking at AoA which is the most overpriced value as well.
Your quandary isn't unique - it's just a scenario that does NOT fit the Disney mold very well at all.
Once you accept Disney can't fit you well... and you open yourself up to 3rd parties... the sky is the limit and it gets much harder to filter down what is really important to you to make a good choice.
But you can find suite hotel rooms with 3 beds for under $150/night inclusive... for a total stay under $800. Like The Towneplace Suites just for instance.. the more you dig and the more you offer shop things could get even better.
TLDR - Your situation exaggerates the Disney difference because you need an offer they really don't have a product that fits well