Its a really lovely room! what a great place for kids to share. I like kids sharing rooms. I think you need another colour to tie it together. I would suggest a blue tone.... teal, navy blue, duck egg blue. to tie it together. Its a little to pale and looks sparse, but actually isn't. I would leave everything exactly as is, BUT, paint the back wall behind the bed teal and find a simple navy blue wall decal that is fun and kid- like maybe one with a sillouette of a boy and girl playing. I would paint the wall behind the sofa duck egg blue. Then I think it would suit both kids more and look more kid friendly. the blues will balance the pink and cream, but because you have a pale carpet i don't think it will look too dark. don't worry about making it totally kid like, its a room they will grow with, not a kindergarten, and it also needs to peaceful and restful for sleeping. besides with their art on the walls and bright toys everywhere it soon looks bright and kid like. Good luck!

You can work with your currant wall color or go more yellow - that is up to you. If you do decide to go more yellow. get some small inexpensive sample bottles at the paint store, paint some poster board and hang it on a wall for couple of days because getting the right buttery yellow can be hard. A soft yellow and lavender is pretty together but I also like the sea green. When you said a combo of modern and cottage - that made me think of beach cottages, which often have soft colors (including sea green) and unfussy, calm interiors. You can put a large painting up if you have the wall space for it. Many bedrooms have tall chest, dresser mirror, tall headboard and big TV, all which take up wall space. If you can hang the painting without it being crowded by any of the things I mentioned, it should look very nice. If you wish to do a curtain fabric treatment to a wall and you have the vision of what you want - then go for it. I had a friend who did that in collage - only problem was the yards and yards of fabric needed got rather expensive. So, I would start with finding bedding you love. Simple white is good, and not too expensive. However, you might find something else light that you love, or a quilt or throw for the bottom of the bed and the colors and shades might lead you in a different direction for wall color or accents. So bedding first, then curtains, then see how your wall color is and then add accents and art - although your painting can also be an inspiration for colors.

Not sure if you need curtains when you have wallpaper? It's already a fairly busy room and it may make it feel smaller and heavier, but if you want curtains I would duplicate the same color as your bedspread.

Easiest is just to paint the walls. Stay away from purple and replace your bed spread. Here are some ideas using orange headboards: A light beige wall . Note that the bedspread uses the same colors as in the room ( so brown , beige, orange) or A fun paint job- brown and white stripes. Again, the bedspread uses the same colors ( white and brown). OR A brave color choice- orange and brown pair beautifully with a deep blue or aqua.