I believe a light grey would look nice behind the blue in the map - it needs to be a perfect shade of grey as grey is hard to achieve. Possibly experiment with various colours - I usually paint on board using sample pots first then hold them up in large sheets to see what suits the area... This gives you an indication of where throws of light will capture the actual colour and which shades suite the room without having to paint on the walls. The board base colour generally needs to be as close to your existing wall colour to achieve the closest match.

Hi senba, Great suggestions above! Yes, use the wallpaper background... but keep it really,really light blue. It will keep the room homogenous and will retain the softness of your paper. That is going to be a very pretty, very fun room when complete.... please post a picture! Elizabeth Cabell, ASID, CID

On your paint problem I can't be much help. This usually happens because of damp -- please get a damp expert to make sure that there isn't any damp lurking in your walls. I had this once when I had pipes leaking inside the walls. I didn't know that. The other alternative is something like painting before the plaster is dry or some kind of chemical mismatch. I do know you will have to scrape all the mucky powdery stuff away and start again, at least on those areas. Don't try to seal and prime and repaint until you know exactly what the problem is and how to fix it.

I think it would depend on the color you are going to use for the curtains and bedding. I think something very neutral on the walls such as a light brownish taupe would give you the most flexibility. I would take the wallpaper into a few paint stores and get some ideas from the people who work there. They can be very helpful.