Did both bathrooms 2 years ago.
I did the demo down to the studs. (broke up the cast iron tubs with a BIG sledge hammer. Too heavy to get out intact.)
Plumber did some re-piping (already was plastic, so, easy)
Plumber and 3 helpers hauled in the new cast iron tubs. ( I watched.)
I applied, taped, and painted the new sheet rock and cement board on walls and floors.
The next door neighbor, super tile guy, did the tile setting and grouting. (Worked well - finished the first one, demo'd the second, and finished it, all in about 3 weeks)
Plumber was busy, so I set the new toilets and a pedestal sink (Still in the midst of the housing boom, then.)
All Kohler fixtures - tile from Home Depot
$3652.80, sore back, and a happy DW.