I think I'm going to try being a vampire (mainly because I'm running out of new things to do in the game).
The best time is when you,
1) Never Feed - Play the entire game as a Stage 4 Vampire, 90% of the game is hostile towards you anyway.
2) Master Illusion - Use the gift the Vampire is given as you will need it to do quests
3) Master Conjuration - Lead your Dead Thralls
EDIT : I was in a hurry...there are others
4) Master Sneak - You will need to be very sneaky
It wasn't until my 250 hr level 60 Vampire that I realized you can still do quests and how interesting it would be to play as a Stage 4. I restarted a new char and played her to level 60ish.
256 days passed
253 days as a vampire
Necks bitten was never on the list. You must bite at least one to even have it listed. I used the Cannibal perk to actually GAIN power from feeding. It works like a
vamp ... um, champ.