What if UO or IOA are at capacity?

[bchbetha]

What if we want to take a break and return about 6 or 7pm? Should it be easy to get in then?
Does being an on-site guest guarantee us entrance or give us priority if they’re at capacity?

per their website, onsite guests have priority. It doesn't use the word guarantee.
But, they have been letting people back in around 4pm on capacity days. You can start following Universal on Twitter for pics and capacity updates.

 

[macraven]

Onsite guests has priority to enter the park.

 

[nkereina]

What if we want to take a break and return about 6 or 7pm? Should it be easy to get in then?
Does being an on-site guest guarantee us entrance or give us priority if they’re at capacity?

We saw the long lines closer to closing, but as others have said, you'd use a separate line for priority entrance as an on-site guest. Not guaranteed, but I haven't really seen any reports of on-site guests being turned away.