Vampiric Ecology
In a fictional world, some consideration should be made for how powerful you make a being in that world, and what the ramifications of such a being's existence truly are.
For example, early vampire lore featured a much different vampire from what followed. The stories stemmed from bloated corpses. Since people didn't know about the processes that cause a rotting corpse to bloat, some thought that the bloating was a result of the corpse trying to come back to life by rising at night and feeding on the blood of the living. Some drank blood, some spread disease, but they weren't especially powerful or smart, and could be killed by destroying the body. These weren't constrained by many rules. One English folk tale features such a creature picking apart the lead work in a window to get at a girl.
These were manageable and didn't need much balancing.
Then you get Dracula. A powerful vampire with multiple abilities, who is much harder to kill, and can rapidly generate further progeny if he feels like it. These kinds of vampires are constrained with a collection of rules. They die in sunlight, they have to be killed with a wooden stake through the heart, then decapitated and burned, they must be invited before they can enter a person's home etc. This model has remained relatively consistent with minor tweaks over the years.
Then came Anne Rice and the concept of the emo lovelorn not necessarily evil vampire. They were still constrained by rules, and had self governing bodies etc to further restrict unoward activity or reproduction. But it made the vampire the romantic interest in such stores.
Enter Twilight. Now you have vampires with even more advantages, and no real weaknesses. There's a marginal constraint of a ruling body somewhere, and a vague fear that an angry mob could cause them problems, but neither is a realistic constraint on such a population. There's no reason that the population of such vampires wouldn't have exploded to the degree that vampires would be running the world. This is a good example of balance fail.
In conclusion, if you want to make an interesting monster, take the monster's environment and what impact such a beast would have on the ecology into consideration before you go off and make a jackass vampire who's greatest weakness is that they sparkle in the sunlight and can only play baseball in rain storms. Aww..