When the new property manager went out to meet the tenant and do an inspection, he discovered that the fiberglass in the tub was cracked.

But, electric is the least maintenance and cheapest to install.One thing I did when I refurbished the old house on the Canadian border, is really insulated it - blew insulation into the exterior walls, under the house and in the attic I put really thick fiberglass insulation. 

In Mass, that means that all components are double-wall, non-corrosive (fiberglass). 

I only cheated on the lower 1/2 bath with a code compliant AAV.We did all the work ourselves so labor was just the fun of doing it.Cost of materials: Main Bath about $2k, 1/2 baths about $225 each from my spreadsheet.We got most of the materials on sale at Lowes: Good quality fiberglass Bath tub $125 (small chip hidden by tile) the toilets $35/each (both non-stock returns), double vanity $175  (side against wall damaged).All the shower stall & floor porcelain tile 75cents/sq ft from auction, Pex, PVC & fittings $185, all elect $100, 1/2 bath vanities $35 each (slight side damage hidden) Lighting $75, all mirrors $100, shower diverter/faucets $275, exhaust fans $30 each on sale. 

All 3 of mine are the small drop in fiberglass kind.  

If you decide to stick with steam make sure any exposed piping is adequately insulated with fiberglass - we had a problem with higher-than-average heating costs which we discovered was due to inefficient heat transfer through exposed pipes. 

I don’t know if it’ll damage your shower pan liners or acrylic/fiberglass tubs.

I really prefer the look of a 1-peice fiberglass unit with no seams to collect water and mildew.

3) Medium grey wood-grained Waterproof vinyl flooring (WVF) throughout, with brushed nickel light fixtures and hardware, or Coffee wood-grained WVF with Oil-rubbed bronze light fixtures and hardware4) Keep the master-bath shower as it is, which is a medium blue fiberglass, and just replace the door with a modern one and trim in some coordinating hardware and glass tile, or totally tear out the shower?

If it's a fiberglass tub/surround, it might be worth replacing as the difference between that repair (because of the labor hours involved) and replacement could be negligible.Another thing to consider - water does not leak straight down.