I like the roman shade. Think the valance idea would be to busy and heavy for that great space.
You could do roller shades which take up less room and can provide privacy. Another option is a cellular shade or a natural woven shade. Wovens you can get with a blackout lining as a option.

Lots of options

Agreed, roman shades feel a bit cleaner and contemporary if that fits with the style of the house.

I agree with woven or roman shades. You could also do 2 inch wood blinds if you need privacy but want to keep the light.
http://houzz.com/ideabooks/3454851

Thanks for all the help. I agree it should be shades. I am excited! Moving forward.