It depends on so many things, there is no right or wrong answer. Here is the conventional wisdom following today's current trends (which could change tomorrow):

1. A single floor (either thoughout the home or at the very least throughout the same LEVEL) is considered a higher-end finish and is highly desirable as a resale feature because it makes a space feel bigger or offers a sense of "flow".
2. Kitchen's and bathrooms (and sometimes entranceways) are considered exemptions to Rule #1. Because of the extremes found in bathrooms and kitchens (splash zones and high humidity/water issues), kitchens and baths are allowed (as in by designers and homeowners alike) to have a different type of flooring that is suited to the use of the space.
3. If you must change materials (because of kitchen/bath) then try to maintain a consistent colour (as in tone-on-tone) to the rest of the flooring so that the sense of "flow" is not disturbed.
4. Ignore rule #3 if the kitchen/bath is being treated as a separate entity with it's own colour schemes. Respect the theme of the space and install appropriate materials in colours/textures that continue the theme.
5. Personal use/expectations trump ANYTHING on the list above. If you want it, go ahead and have it. It's your house. It's your money. You need to be happy in your home spending your own money. If you want bubble-gum pink Ms Kitty carpet sitting next to flaming orange linoleum, then have fun. It is your home.

How's that for an answer?

OMG!!!! That is so fantastic!! Thank you for your response. I totally agree on the one floor throughout the home, maybe a wood looking tile. but then i see some of these really great patterned tiles in pics of masterbath, powderoom bath, maybe laundry, etc. So then i think, ok, maybe if i used same color palate in said wetroom area's to add punch. Again, your response was so great and i thank you very much.