What if you do want to cover an entire wall with polka dots? Your best bet is to choose a fun pattern that loosely hints at polka dots but isn't quite so solid in color. These round colored dots in mostly neutral tones are a lot easier on the eyes than say a series of big red polka dots on a white background would be.
The space above is perfect for letter-writing, but this space has everything I'd look for in a curl-up-with-your-computer spot. The fun color and wallpaper and accessories - especially the globe - add energy that suggests tha this isn't your typical workspace.