1/2" drywall with plastic fixtures, particle board vanities and cabinets, and fha minimum grade throughout or 3/4" drywall, 10' ceilings, granite, wood tongue & groove cabinets, deep sinks, 9" faucets, smooth stucco, and full interior trim?

Victorian, Second Empire, Edwardian), particularly those originally built as over/under duplexes or triplexes, will have subfloor assemblies comprised of two layers of boards (the top one may be tongue-and-groove) with a layer of plaster between them.  

Michael Wentzel so you wouldn't suggest using a joint compound in the grooves?

So I'm doing major rehab of a 5 unit in San Diego and scratching my head on one particular "feature" of the buildings.The ceilings are really nice vaulted open beam ceilings with stained ship lap tongue and groove finish between the bay's - it's visually the nicest part of the units.Turns out the roof is - literally - 1x6 tongue and groove, then 1/2" sheathing, then roofing paper, then shingles.

Painted or stained tongue and groove?

Dick - I'll leave it to the pros to answer that one.UPDATE: Upon closer inspection, there are several important additional problems here. 1 - There is a step on part of the slab that is far taller than code allows. 2 - The main steps to my path are not perpendicular to the slab on the sides.3 - The grooves that were put into the patio for cracking aren't even close to being perpendicular to the structure of the house.4 - The staircase coming down from the house and the other step, as well as the landing in front of my door are on an incline.

The process is pretty scary, but I'm beginning to find my groove.

Real hardwood floors (and the vinyl snap together stuff) all is tongue and groove so it holds together and the top edges are even. 

Any ideas for restoring the beauty of old knotty pine tongue and groove.

@Robert Campbell caulk grooves, thinset wall, spray texture, then paint