Wirelessly posted (BlackBerry8530/5.0.0.601 Profile/MIDP-2.1 Configuration/CLDC-1.1 VendorID/417)

I doubt that US would care very much if one threw away the last segment on an award ticket, but if you end up flying US in both directions, redeeming through Aeroplan would avoid any problems: if the overnight stop at PHX on the outbound qualifies as a connection under Aeroplan's rules, you could then get a full stopover at PHX on the return, and get your travel from PHX to Pennsylvania included on the same award; if the overnight stop at PHX does not qualify as a connection, you can make it your permitted Aeroplan stopover, and just have the return trip end at PHX, since Aeroplan permits both a stopover and an open jaw on the same award.