I was in your position just a few weeks ago - my heart/riding plans said road bike, my common sense/budget said hybrid. I was worried that a) I'd buy a road bike, have a few weeks of "honeymoon", then quit or b) buy a hybrid, fall in love with cycling and want to upgrade immediately.
I went to three different LBSs and said much the same thing (a little less ambitious than your plan) - road only riding, beginner, no racing, mainly fitness riding of 10-15 miles per ride, with an occasional weekend ride of 20-30m, budget of $500-$600.
In the end, all three shops suggested a Specialized Sirrus, which according to them, is like a road bike with flat bars (I'm not expert so I take their word for it). I tried it out, but one LBS also suggested a low-end road bike on sale for $50 more than the Sirrus. I tried it and even though the road bike is really low end (it's a K2 Whirlwind and I know there's not a lot of love for the brand on this site), it felt "right" in the way the Sirrus and other hybrid bikes didn't. I knew immediately that this cheap little road bike would make me happier than the nicest of hybrids.