The Mrs. and I are taking a holiday break in Grand Cayman this winter, flying United from Toronto Pearson (YYZ) -> Chicago O'Hare (ORD) -> Grand Cayman (GCM), and flying GCM->ORD->YYZ on the way back.
I have connected through ORD to PHX without rechecking bags / reclearing security, but am not sure what happens when connecting internationally. I also have noticed that the ORD ATS system is on an extended outage for maintenance/reconstruction which means you only have shuttle buses as a way to get from T1/2/3 to T5 for the time being.
YYZ has US pre-clearance so we would arrive at ORD as domestic passengers, which means T1/2/3. Would the outbound United flight to GCM be at T5? If we need to transfer to T5, since ATS is not running, would this involve claiming and rechecking luggage as well as re-clearing security? Or, because it's United, would it be departing from T1/2/3 which should mean no re-checking of bags?
On the way back, we should arrive at ORD at T5, then need to transfer to T1/2/3 for the return flight to YYZ - would the process be: US customs/bag claim/recheck bag/security rescreen? Is three hours of layover long enough to make these connections? (We are NEXUS members so screening times should be on the lower end of the spectrum.)