Heres what I did when I moved.
Siphon half the water out to save to the new tank (if possible, you could use less if you had to). Siphon more water out to rock tubs (this water will be disposed of later). Take water down as far as you can (remove any rock that isn't sitting on the sandbed as the water lowers but leave the rock that is on the sandbed until last). Siphon water to about 4 inches or so. Remove last of rock to rubbermaid tubs. Catch fish and either put them in a tub/bucket by themselves or with a few corals. Don't put the fish in with any larger rock or you risk dead fish with a landslide.
At this point, really I would plan on ditching the sand. No matter how old it is, its full of crap and the amount of rinsing you'll have to do to even get it reasonably clean is immense. If anything is going to cause you problems down the road it will probably be the sandbed (JMO).
So move everything to your new destination, get the tank on the stand and plumb it to the sump. Put your sand in and place a large black garbage bag overtop and put a bowl in the middle, fill your tank pouring water into the bowl until the garbage bag and bowl start to float. Then continue to pour water in on top of the garbage bag. This reduces the cloudiness of the water since your sandbed isn't getting stirred up. Put your rock back in when the water is full by half. Get the tank filled, then make sure that the temperature is all about the same as the tubs/buckets before you put your corals and fish back in. You may have to stick a heater in and wait a bit (or alternatively you could heat up some RODI water and add salt to it and pour it in if you're in a hurry).
Et voila! That should take up about 10-12 hours of your day.
