As I tried to suggest, gently, in my post above, backpack fit is almost as individual as shoe fit. So are many other items you consider important like taste. That's why I listed my personal criteria, since I don't even know what you consider a "pretty" backpack.
If your gear varies so greatly in weight and bulk from trip to trip, I strongly suspect that you need two packs, one for short trips and the other for long. I've managed to get along with only one because for me the only item that varies by length of trip is food and an insulation layer more or less. I also have a pack that can easily be adjusted to fit different volumes by means of compression straps. I even use it as a day pack when base camping (not great, and definitely ugly, but it works well enough that I don't need to carry the weight of an extra day pack).
I notice that you're basically rejecting the advice being given by our members here, many of whom are far more experienced than you. For example, Wandering_Daisy has been backpacking since childhood (as have I) and (unlike me) has spent many years on the staff of the National Outdoor Leadership School. That's your privilege, but, if you're rejecting the advice offered here, it means that you are basically on your own as far as research goes. Good luck!
Edited by OregonMouse (05/06/16 03:57 PM)
May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view--E. Abbey