I moved from a 60g to a 100g, and had all fish in a large rubbermaid with heater and air. All corals in another container with a powerhead. All live rock in a 30g brute can.
This really helps because moving all the rocks, sand, equipment, and putting all back in takes a LOT of time. Then you wait for the sand storm to settle down. Then test....
A container where fish and corals can stay all day long helps a lot. I'd say keep about 30-50% of the water, and replace the rest of it with new sw.