Carpet and Tile
If you can get by with a good cleaning, it's best not to replace your carpets entirely. If the carpet is terribly worn, stained beyond repair, or hopelessly out-of-date you should look into replacing it with something inexpensive and neutral in color.
Cracked floor tiles should be repaired or replaced as well, but remember not to spend too much. All you are looking to do is eliminate a few negative impressions.