Join Date: May 2005
Location: various cities in the USofA: NYC, BWI, IAH, ORD, CVG, NYC
Programs: Former UA 1K, National Exec. Elite
Posts: 5,487
(Not an answer to the exact question, as this doesn't work when booking.)
One way to get around the 4-hour rule is to use the SDC process after arriving at the connecting city. e.g. Book DAY-ORD-HPN. When you arrive at ORD, check in again and you can change to flights leaving the next day.
In theory one could extend one's stay at connecting airport for days. Of course this only works for Golds and above (free SDC).