Use Crushed coral sand for the bottom of the tank, I prefer 1mm grain and minimal amount is about 2" thick, 3"-4" preferred. then stack up the live rock for biofilter/ for fish to hide in.
Also I've worked with canister filters, I much prefer a sump due to it's easier to add stuff to the filtration as you go on. eg: biopellet reactor, uv
sterilizer, chiller etc.
Plus with a sump you can design it as you want and hide all the heaters, skimmer etc under the cabinet rather it being shown in a tank and they're much easier to maintain and work rather than pulling apart a canister filter when you need to do maintenance.
Also with a sump, if your going down that road, would be recommending a refugium setup, best biological filter money can buy i believe.