playboy's actually pretty good these days, to completely jump the topic. Vivid is good, in general. Ask her what she thinks she's gonna see... what she wants is gonna direct your choices a lot. if you want soft, look for female directors.
http://goodvibes.com has a policy that they try to have videos that "focus on women's arousal and pleasure" so that may be a place to look for some ideas. Read their Video Selection Criteria" to see what I mean.
good luck!!