Porcelain is much harder than ceramic. There are non stainable epoxy grouts but they are more expensive and harder to work and clean. I haven't see grout crack unless the tiles are not properly bonded and are shifting/cracking or if you are talking about very old tile. Perhaps the subfloor has moisture problems?!
Another type of flooring you might consider is Pergo:
This floor has the look of wood and a great reputation for durability.
When we first moved to Dallas, I worked for a Natural Stone company that sold granite, slate, marble, lime stone, etc! Most durable floor you will ever install is granite! It works! A lot of people think it's expensive, but it's not when you go with granite tile and it lasts twice or 3 times longer than any other floor, including ceramic tile! I am talking of course about your kitchen floor, dining room and possibly family room or the place your family gathers together most often. For the rest of the house, I would go with wood personally, especially since these days, you can get your wood treated to resist the most strong of scratches and spills, including pet accidents! For the bathrooms, tile too! That's what I would do anyway!
I am sure the wood floors may be easier to take care of now but mine were a disaster. I refinshed them once and put a 1/4 inch top coat of Val-Spar urathane on them but my kids scratched them badly anyway. Oh yeah then there was the time my fish were fighting and knocked the undergravel filter tubing out of the tank- 55 gallons of water warped 3/4 of my 500 sq. ft of wood. Not a biggy in the end thou cause like a good neighbor State Farm was there! Since I put the floors in myself (on a floating subfloor) my cost was low and I actually made enough money from the insurance to redo all the affected floors, replace the kitchen doors and install french doors leading to my patio. So I guess going with wodd was not that bad afterall- LOL!