Well done for seeing the light and moving over to the Dark side
Kidding
Sand really is the best option IMO, but each to their own. What is your tank size BTW, how many fish will you be removing? If I ever need to remove all the fish, I use a regular plastic storage box from the hardware shop, drain off the tank water into the bucket, and place the heater, filter into here and place the fish in. Then the fun begins
Step 1) Wash all your sand, I mean REALLY WASH IT. The water wants to be crystal clear when rinsing it, when this is done, move on to the next bucket of sand.
This video shows basically how I do it mate
Step 2) Remove all the water (Obviously
)
Step 3) Remove all your decour, and give it a good wash to remove any algae (might as well get the tank looking great)
Step 4) Remove the Gravel and give it a good wash and leave it some where to dry.
Step 5) Add your sand to the tank, add your decour, Half fill the tank, plant whatever needs planting and there you go, Gravel
Sand
Other's may do there's differently but this is how I personally have Changed over to sand in the past, and never had any issues. If you wash the sand Really well, you will get hardly any cloudiness, and your filter won't clog up as bad, I would still do a 10% water change after the tank is slear and rinse the filter media to remove any sand debris that may be in there