Hi - I think I would go with something either the same or similar to these because as you say it will be more difficult to find a blue to go with the blue in the wallpaper - so, personally I would be tempted to go with a contrast colour to the brown and also you don't want a dark colour so have a look at these :

http://www.benjaminmoore.com/en-us/paint...

http://www.benjaminmoore.com/en-us/paint...

http://www.benjaminmoore.com/en-us/paint...

Here are some pictures of teal and brown bedrooms - although you don't actually say if it is a bedroom you are talking about or a living room etc - but no matter what room the wallpaper is in really, at least it gives you an idea of how the colours above would look :) View the picture below with a similar colour to the ones I have chosen:

Anyway, hope the above helps :)