did you compare like for like ?
1 night at RPR will get you 2 days of unlimited express passes.
You can check in from 6am and even if you won't get a room that early, you will have a room key to show at early entry, and you'll be able to print your express passes.
When you buy express on the side, there are 2 options. Single express (1 visit per ride, per pass day) and unlimited express (unlimited visits for each ride, per pass day)
with the hotel you get the unlimited express version
you're going in october, so 2 days of unlimited express passes for 2 adults cost $399.96+tax
A Standard King Room ar Royal Pacific, for the same date used in my sim, costs $294 + tax
so buying express on the side is actually $100 more expensive than staying onsite for that night.
Maybe you didn't realise that 1 night at a deluxe hotel in UOR gave you 2 days of unlimited EPs, or maybe did you price the single express pass.
but usually, staying onsite at an EP enabled hotel is quite cheaper than buying the express and staying offsite.