I have SPDs on my hybrid and was happy enough with how well they worked. I have Nike touring shoes for the SPDs, which I now use only for my spinning class (b/c I don't ride my hybrid anymore). On my road bike, I have Look Keo pedals and Sidis Zeta Mesh shoes. It took a bit of time to get used to the Keos and road shoes.

In comparison, the adjustment period with the SPDs was shorter. That said, I prefer the Keos over the SPDs. The pedals are light and, after much practice, very easy to get into to. I like the bigger platform. I also prefer the Sidis. Road shoes, in general, are better ventilated than MTB or touring shoes, which is great when you're riding long distances in the heat. They're also very light and stiff. My only complaint with the Sidis is that the toe box is on the narrow side. I sometimes find that they get a little tight when my feet have swelled. I even went up a size when I got them. If and when I purchase another pair (Sidis reputably last forever), I might spring for Carnacs.

Just talk to the guys at your LBS about them. Everyone has a favorite it seems and they can tell you the pros and cons of each type. Whatever you choose, I think it's worth the money to have a professional fitter adjust the cleats so that they're in right position. It's easy to develop knee/foot/ankle problems or to experience discomfort if they're not in the right position relative to the ball of your foot. I had that done alone with a professional bike fitting and it was money well spent.