First case: 3
Second case: 3
Trinipshere is ALWAYS the last thing to be applied. There's no timestamping involved whatsoever. It goes cost increasers, cost reducers, Trinisphere. If you go to play Ancestral Recall, first you apply the SoR, so it costs 1U. Then Trinisphere sees that you're trying to pay 2 for something, so it bumps the cost up to 2U. In short, everything that has CMC 2 or less only costs 3 when Trinisphere and SoR are in play together, and everything that has CMC 3 or more gets increased by 1.
EDIT: Ok, so I didn't get my response in in time.
