I have encountered 2 vampire attacks on cities thus far, one of them managed to kill a guard, the other completely failed (I assume the difficulty of the vampires gets worse at higher levels, im below level 20).
Yes, the level 81's usually report "ghost towns". The higher levels have higher level vampires that spawn, and these vampires greatly out level the guards and the NPCs.
Can people please post what quest path you have taken - vamp or dawnguard.. How far into the quest they are and the frequency of the vampire attacks.
Logic would dictate that if you are a vampire and support them, the attacks would keep happening.. Likewise if you were in the dawnguard and wiped them out (I assume that is what you would eventually do) the attacks would stop.
Can anyone confirm this?
I've been gathering as much information as I can about this so:
The attacks seem to be more frequent after fast traveling to a city/village. When you fast travel there seems to be a chance for the vampires to spawn anywhere inside of the city.
If you fast travel to a dungeon/cave close to the city, the chances seem less likely for an attack. If you do get an attack, and the vampires do not spawn inside of the city, they will usually spawn right at the main gate. For villages they seem to spawn at the road entrances to them.
From what I have gathered the attacks will continue regardless of which side you choose, or if the main quest for Dawnguard is completed.
I will edit this post if I remember anything else.