Facial hair style depends largely on the shape of your face.
I've always had an intuitional eye for what is "attractive" and when I sent a picture to Chase to have caricatures drawn Chase pointed out that I style my facial hair to create a strong, masculine jawline. Anyway, provided that your stubble doesn't make your face look weird (or your chin/neck look fat as it can if the stubble goes out of control) then a stubble is a great option. If I remember correctly, I read a study that showed that around 7-10 days of no shaving is what is "optimal" for lengthy and ruggedness.
Also, your facial hair should compliment and work with whatever hairstyle you have up top. I rock a messy undercut for the most part and when I've had it cut or trimmed too short then I have to change/adapt my facial hair, as well.
Here's The Idea.
-Richard