I think you just take Changi airport and replicate it everywhere else.
I've never had a bag lost there, nor had my bag miss the connecting flight when I was transiting. Now I live here, I have never had to wait more than a few minutes for my bags to come off the belt.
Immigration is quick and efficient, even for non-Singaporeans / residents.
It is light and airy as a building, even T1 which is pretty old by now.