A couple of random ideas if those don't end up working.
Skirt Sports makes really cute skirts and can come with several different length pants beneath them from bike short length to capri to full length pant. I've seen them in several of the running stores we have around here too. I think their site gives a list of the stores that carry them.
Their full prices are steep but Sierra Trading Post sometimes clearances out some of their stuff for a good deal. STP regularly doles out coupon codes (automatically added by clicking on link in their email) if you are on their email list, but it's sometimes good to put it on a secondary email account if you have one cause I probably get at least one email a day from them. They can be kind of picked over in sizes or colors but when they do have something I want in my size and have a decent coupon code, the price is almost always the best I can find.
I really like Lucy's Propel shorts but those might not be long enough for what you have in mind. They are a 5" inseam I think the site said. They are a bit above my knees for me though I am 5'2". Definitely longer than other running shorts I have though and really nice. http://www.lucy.com/Propel%20Woven%2...r=LUCY%20BLACK