OH NO I'm becoming obsessed with carpet.....

Debbie One trick is to use cheaper carpet and the best padding they have.  It makes the carpet wear better and look more expensive.  Also may I suggest not going with a brown carpet.  People think that it hides dirt etc, but what is shows is every little white lint and white dust.  Also for selling purposes a more netural color might be better.  Like a taupe or beige, dark makes a room look smaller and brown is very taste specific.

If the floors need sanding do it first, before carpeting, sanding floors creates fine fine dust everywhere, you will need to sweep walls and clean clean clean after.  Plus the smell of the sealers takes days to go away.  If they aren't to bad just clean and polish them I get a product at Home Depot that really does wonders. Clean first, several times if needed, with ZEP COMMERCIAL HARDWOOD AND LAMINATE FLOOR CLEANER and them use REJUVENATE FLOOR RESTORER AND PROTECTANT , its's only 1 coat application!  My floors have really come out very shinny and beautiful. 

Good luck on this project - I know how they can snow ball and cost more and more!!  Do you own this property or are you doing this for a client?