Just got word from Aer Lingus that they're moving from T5 to T3 at O'Hare:
Since I'm flying Business Class from O'Hare in April, this makes me happy. The T5 Swissport lounge that AL used was pretty bad, according to reviews and photos I've seen, so I wasn't planning to use that one at all.
The arrivals into T5 @ ORD were great, especially given that pre-clearance was done @ DUB. However, as you say, the Swissport lounge was not up to much. Small, no windows, and limited availability.