You should delete your previous post and stick with just this one if those inspopix are the way you want to go with the room. They look very contemporary and not too 30ish, which you mentioned in your other post. Search the box above for the phrase "pink guest room" to get some inspiration.

I love that color, so cozy and organic. :) Your furniture is light, which helps the brightness factor ... I’d just look for art you like and use that. Maybe canvas prints, or art with light backgrounds. Green, to me, is very neutral — you could add light blue, white, cream, lighter greens, etc. I don’t like to suggest specific art because it’s a very individual thing, but ... A map of the area, like this, would be fun — A decorative mirror might be nice, too, to reflect light and color. Definitely do a search for things like ‘art for dark green walls’ ... ‘lake art’ ... etc ... lots of inspiration comes up.

You completely ignore the slant and decorate below it, as you would with a regular wall. Pretend the ceiling is my (very uneven) line here, stay below it. Doing that will give the comfortable and cozy feel you want. :)

What are the paint colors in the rest of the home? What will the flooring be? My first thought for your room (without knowing more) was BM Pashima. It’s a warm and neutral greige. I’ve always painted my guest rooms in lightly warm colors, and gotten lots of compliments for how cozy they feel. I think navy curtains sound great, and I’d keep the beige sheets. You can see how Pashima looks deeper depending on light (do a search for lots more examples) — Being a greige tone, it looks good with warm or cool colors. In this light, it takes on a more gray feel: It is fairly monochromatic, I don’t know if you like that (I do), but good for adding in accent colors. I’m not sure what a lighter version on the Pashima color strip might be, but it might be worth looking into if you feel this is too dark.