I'll be laying hardwood in LR, DR, Entry, and Hallway and I'll be laying 12x12 ceramic floor tiles in K, Breakfast, and Utility. I don't have any experience with hardwood but I'm competent with tile. There will be four areas where the two floorings meet. Can anyone give me a reason to do one first before the other?

Tile first. Laying tile is considered a "wet trade" and therefore, effects the jobsite humidity levels. There are other practical reasons as well. Lay the tile first.

Thanks. I was leaning towards doing the tile first but hadn't thought of the humidity factor. I was mostly concerned with the potential mess with the glue and grout. If outside pressure (spouse) forces doing the hardwood first, how long in days/weeks would you suggest I wait before starting the tile?

There are many reasons, take Gary's advice on this.

If you install the wood first, you may see some compression set cupping from the wood gaining moisture and swelling, once installed tight. It may go away eventually, and then it may not.

OK, so if we didn't follow the advice to install tile first (I didn't figure it mattered - oops) how do we minimize the impact of tile after wood?

Place your palms together, with your fingerstips pointed to the ceiling about chest high.

There are a lot of reasons besides the moisture and evaporation going on. Laying tile is messy and gritty. I don't want to be carrying buckets of water, thinset and grout over top a hardwood floor. Going back and forth to the wet saw, then dripping a cut tile back with you. I have had buckets of thinset come apart just carrying them from the weight and the mixer paddles weakening the sides. I think it is also easier to transition from wood to tile than the other way around, you can't or should not shim underneath tile.

Jerry's right. These are the other practical reasons I was refering to. If you have already laid the wood and are going to add tile, cover the floors to prevent damage and keep the environment well vented. By that I mean (so none will misconstrue), to not allow humidity to build up inside the home by cutting the tile outside and using a box fan near your work area to draw out moisture to the outside.