Another vote for a road bike.
The rider position, skinny tires, lighter wheels, and absence of suspension will make a road bike faster than most hybrids. If you typically ride at, say, 14mph on your hybrid on calm flats, you'd ride at around 18 on a road bike, 17 on a cross bike.
I enjoy my cross bike and got it primarily for touring and 100+ mile rides. They're good all-around bikes, and reasonably affordable; I got my Surly Cross-Check for around $1000, including getting the LBS to set it up with a triple crankset. However, it does feel a tad slower than a full-on road bike.
Also, hybrids are usually comfortable for shorter distances, because you're sitting more upright. But you're putting a lot of pressure on your lower back and saddle, so some people find that a lot less comfortable after 50 near-continuous miles.