Typically we match the bathroom floor to the shower floor. If the bathroom floor tile is too large and slippery, we'd cut it into smaller pieces. Do make sure that your shower floor tile is not slippery when wet. There are products that you can put on the tile afterward to add some grit if needed. Your shower most likely has a threshold and make sure that is well-delineated so you won't stub your toes. Keep in mind that natural stone requires more maintenance and is not as resilient as porcelain tile.

Heed MillWorkman's advice. Any change of plane, whether it is wall to ceiling, wall to floor, wall to wall, etc.. will almost always require caulk of some sort. !00% silicone for anything around water. In other areas, a siliconized caulk, or paintable 100% silicone caulk can be used. I have done a lot of painting, either for myself or others, and I learned from an experienced pro to put a light layer of caulk in corners, around mill work, and wall to wall/ceiling/floors to prevent the paint from cracking/splitting. Just my 2 Lincolns worth.

Maybe do the 2 bedrooms with carpet and then just match the othere 2 spaces with the same tile. I think trying to match and miss the laminate would be worse.

Whats standard? Might depend on where you live. :-) In Arizona, my tract builder routinely used grout to seal the gap between the tile and the baseboard (they used *nothing* between the carpet and baseboard). I never had any complaints with the grout, even after our house flooded. In Texas, my tract builder routinely used caulk to seal the gap between the tile and the baseboard (again, nothing was used between carpet and baseboard). I, personally, dislike the aesthetics of white caulk (to match white baseboards) running along the bottom of every wall -- it has always reminded me of a bathroom. When I viewed the model homes, it felt like I was walking through a ginormous bathroom. :-/ As an experiment, my husband beautifully installed beadboard and beefy baseboards in our pantry, and when he sealed the baseboard/floor, he used a very thin line of caulk that matched the *grout*. It looks a million times better. I remember asking a similar question here on GardenWeb, a few years back, when my current home was being built... And I think it was a member named "worthy" who mentioned using caulk as a barrier for insects. That pretty much sold me on the idea, since we have fire ants here (had over 300 scorpions in our house in AZ, the first year we lived there; I'll take fire ants any time!). Unfortunately, you'd have to caulk/grout EVERY baseboard, which tract builders won't typically do if you have carpet anywhere. Based on your photos (except the first one -- that's really sloppy), I love that the builder seems to have tiled *to the wall* and then put the baseboards on. My builder -- sigh -- tiled roughly 1/4 of an inch away from where they anticipated the baseboard would be (I actually have 1/2" of caulked space between tile and baseboard in a hallway), so I have a ton of horizontal caulk lines all over the place that trap dirt and shrink up. Scrubbing caulk with baby wipes is fun. :-/