Depends on the tile and the style. Either works, or a combination. Are you staying period specific?

I prefer porcelain tile on a floor, for a couple of reasons. It is more durable, think Corelle verses stoneware. I have porcelain tiles on my fireplace surround, and while it does have some cracks in it, from a metal chair dropping on it, it doesn't stand out as needing to be replaced, because the same color is throughout its core. However, having said that, we had to remove some from the kitchen walls, and it was very hard to break up to remove. So, it was sort of overkill for a wall, because the chances of something dropping on it, are next to zero. But for a floor, that is a likely possibility.

Laura,,,not enough info. either will work fine. usually porcelain is colored all the way through to the underlying clay body. this makes it a better choice if the tiles get chipped or broken (with ceramic, the white clay interior is usually visible if it breaks) otherwise, not a big difference. both work equally well in bathrooms.

as far as easier to keep clean,,,huh? they both clean just as well. grout size is determined by the type of tile you get. longer larger tiles require larger grout lines, porcelain or ceramic. Just because the tile is porcelain, doesn't mean you get smaller grout lines than ceramic!

Ceramic is easier to cut than porcelain if your new to laying tile. But porcelain is stronger.

Porcelain tile IS a ceramic tile...just fired at a higher temperature for a harder product. A good pt is what is referred to as a "thru-body" tile. As Beth mentioned, the colour goes completely through it. The cheaper porcelain tile is a "face porcelain" and the design/colour is only fired on the surface,,,

Porcelain tile is also more dimensionally stable. That is to say it will absorb LESS moisture than ceramic. In fact, ceramic has a history of "tenting". That is when the tile swells to the point where they break the bond with the mortar/thinset below. This is common enough to make people think about the product they are using.

In a wet area, like a bathroom, I would prefer to see a porcelain tile. But the choice is yours.