Absolutely no problem changing up the carpet. Things to watch for......make the transition in a doorway, an opening or along a visual break in the rooms (like the corners of the walls). I would stay in the same colour range, but just go to the other end of the spectrum rather than change the colour completely.....like light grey going to dark grey, not light grey going to navy blue. You want the separation but an easy transition on the eyes.

Love blue tiles. Depending on how much sun and how hot your pool gets in the summer should dictate what color it is. We live in Arizona, so cool blues work best. Our neighbor has brown tile and a dark pebble tech pool. Looks like a swimming hole and gets really hot - 94% water in the summer. They obviously didn't think it through.

Sophisticated start. You could go with black and white photography, architectural pieces, art pieces- anything you love on the wall. Then, add pillows in the colors of the art work. If you want to stay more monochromatic, think in terms of textural interest, such as a shag area rug, pillows with seam detailing, etc.

I'd like to suggest that the most important thing here is more about who is using the room. If It's a child's bedroom use lovely children's curtains - there's so much around and any pattern could pick up the wall and floor colours. If a guest room and not used often I'd suggest a beautiful velvet or good quality Linen and forbid the little ones from going in to that room!!!!!! alternately a blind attached at floor level could be raised or lowered so the view is still there but with privacy from waist height perhaps. Good luck. Bee