Nozzle layout, [including 12-16 inch nozzle for a bayonet or U-tube heater?] Add at least 1 extra 3-6" nozz
Instrument [nozz] layout
Is a Cleanout M/W worth the price?

If you need Fire-Case venting, buy a Relieving Hatch for the Roof 'Light Hatch' M/W

Easy, protected access to the roof area containing the Sample Thief hatch, the Breathing/Conservation vent, and a tie-off lug/nozz.  Tie-off is much cheaper than putting a handrail all around the tank roof

[no such thing as a flat floor with lapped floor plates]thus;
Floor down a little - putting the last puddle in the center where one 'slurp' of the Vacuum Truck can finish cleaning the tank for entry, or;
Floor a little up, so that 2 guys with squeeges can push the last little bit out the Cleanout M/W

Water drawoff sump?  If so, keep it within easy vac-hose reach of the side M/W.

Floor drain?  If so slope the floor to the sump.

If the side M/W is smaller than 36", put a grab-bar above it for easy entry/exit for us large guys.

Make d@mn sure that the floor plates get a protective coating [asphelt, coal-tar epoxy, etc] after sandblasting, prior to delivery to site.  And add some magnesium ribbon cathodic protection the the floor while it is being laid. floor underside corrosion causes more repairs than everything else, combined

While doing the site dirt work, bury at least 20-ft of ground cable [works better than just a rod].  Then Cad-Weld that cable to the tank grounding lugs, preferably 2 places.  If a ringwall is used, run this cable up into the pour, turning it out about 4" below the top of the ring [keeps it up away from the mowing/weed chopping].