One thing about panniers is that you have to decide whether you want to take them with you when you leave your bike outside. The nicer the panniers are and the easier on/off they are, the more tempting they will be to thieves. I'm guessing you'd be taking those babies in with you once you arrive at work or at the store- they are very appealing!

My panniers are just for grocery shopping- they didn't cost much (less than 1/4 of what those Queen bee bags cost) and I have them pretty firmly attached to my bike's rack with several extra hidden zip ties so that taking them would be a bit of a hassle. That way, I feel ok leaving them on my bike while I'm in the supermarket, only taking my re-usable grocery tote bags in with me to fill. Thus, I chose to put my panniers on as a permanent accessory for my 'errand/shopping bike'.