Get the professional sander guys in to repair the living areas and kitchen but don't go too dark with the stain as it will kill the lovely grain in the matai. I'm thinking a couple of tones richer than the timber knots showing in your photo, definitely no yellow tone at all. In NZ stepping on to carpet especially in a kiwi winter is so much nicer than a cold floor board shock!!! A nice area rug for the lounge and you're done.

I'm guessing you are from NZ (kiwi) :) The handy sanders did our floors - http://www.handysanders.co.nz/. They did an AWESOME job and are reasonable priced. I would definitely recommend.

There are more cons than pros, I'm afraid. Near black floors will show every speck of dust and need constant maintenance. They also will suck up a lot of light, so you need to add lots of extra lighting. If they are shiny, they also show marks just as a mirror does. They are not the best for re-sale properties either, as most people prefer something more medium toned for the long term. I recommend going with a more classic floor, and then adding black accents in furniture, etc. Your kitchen could be mostly white cabinets with some very dark stained sections. Here are some ideas from modern to traditional. Click on the pictures to enlarge them.

Beauty and practicality; Mmmmmm ..... When it is something that you love .... real wooden floors. Now vinyl just gets dirty , Ply looses it functionality, real wood however gains a patina. You want that. People pay thousands of dollars for that. Go with the most genuine example that you can afford of what you love. Factor in your budget and add to it, an area at a time and be pleased that your life gives character to it every day. By analogy; A mahogany french polished table will just give you a nervous break down every time someone doesn't use a coaster ... a hardwood table can be replenished over and over with hard wearing protective surface .... which you can repair. If you love it, if it adds genuine warmth and character, you won't mind maintenance. You won't be saying ...." look at this floor , isn't it amazing? It looks just like the real thing?"