You all are lucky. I avoid caffeine as much as possible because I am hyper sensitive. At one point, I drank coffee before work outs and I was a raging beast in the gym but the feeling of hyperactivity never stopped and I couldn't sleep for the next few days.
I'm hypersensitive, too, but that doesn't stop me from my morning 14oz cuppa joe. I always keep both regular and decaf coffee on hand and dial up my desired level of caffeination, usually 1:1, but I'll often do 1:2 or sometimes 2:1. I seldom have any coffee after noon, but when I do it's all decaf.
I get some weird results. Very often that 50% caffeine coffee I had at 10AM will keep me up past 3AM. And I can always tell when it's the caffeine and not just simple stress or insomnia.
Occassionaly, when I've had coffee every day for a stretch, I'll get to the point where my mind is playing ping-pong all day long. I can't stay focused on any one task, and I go just a little nuts. Then I take a day or two off and my mind is noticeably calmer. It's a great feeling. I suppose it's like the old joke about hitting yourself in the head with a hammer because it feels so good when you stop.