Is that your only complaint about it? Installing a wall and door shouldn't be too difficult. Without seeing your style it is hard to suggest something. Have you considered sliding frosted glass doors to close the area off? Search the box above under Photos for sliding glass barn door and you'll see many ideabooks to help you make a decision. Just this week a Houzzer completed installing a pair to close off his bedroom and the job turned out great!

I would suggest changing the mirror similar to one in the photo http://www.secrethiddentreasures.com/vglepu068.html

Instead of the clock above the toilet I would put a peice of wall art to compliment the color
http://www.secrethiddentreasures.com/vgshd-adb5052-53-54-55.html

Add a nice towel bar facing the tub, you can get this from home depot depending on your style
http://www.homedepot.com/p/Danze-Bannockburn-24-in-Towel-Bar-in-Oil-Rubbed-Bronze-D441602RB/202359735#.Ud8Ajr7D-cw

Two rugs, one facing the bathroom sink and another by the toilet, the one for the sink can be seen in the link below
http://www.homedepot.com/p/Home-Dynamix-Spa-Mint-Green-20-in-x-32-in-Microfiber-Bath-Mat-5-TSPA-43/202980783#.Ud8BdL7D-cw

Bathroom Light above mirror
http://www.lightinguniverse.com/bathroom-lighting/minka-lavery-3243-77-cashelmara-3-light-bathroom-light_g419399.html?isku=4015514&linkloc=cataLogProductItemsImage

I hope this helps