Would it feel like a four star meal eaten by a starving man? Would it be a powerful and brief rush like cocaine? Would it feel similar to the high of other drugs? Pot? Ecstasy? Heroin? Would you prefer it was like a sommelier taking in the subtleties of a red wine - some great, many sub-par?
Ignoring the question of how often you must feed as a vampire, and what - if any - addiction and consequences of forgoing blood there might be – how would you prefer it. Let’s also imagine that bitten people neither have to die or are made into vampires.
I’d prefer it to just feel like normal eating, but to be more filling, so I could get by on as little as possible. I’ve got enough psychological issues with eating to make me happy, and I wouldn’t want that to carry over.
If I had to guess, though, it would feel like being in hypoglycemic shock and getting some sugar into your system. But, seeing as the shock can feel like a panic attack, there’s no way I would prefer that. Agoraphobic vampires? Yuck.
Well I always imagine vampires to be closer to the original concept of a reanimated corpse that must feed on the living, rather than the suave Ann Rice beings that have saturated popular culture. I Imagine that it would be like being filled up with hot soup after freezing in the snow for days. The effect would last longer though since they are dead and presumably metabolize at a very slow rate. Perhaps their bodies have special insulative properties to keep the warmth longer then would be normal in a human one. The more of their power they use, the faster they need to refuel and the colder they become until they are back to the reptile like room temperature.
IIRC, in one of the stories in the anthology “It Came from the Drive-In” , a teen girl turned monster described it as being like eating her favorite foods – milkshakes and such. Suzy McKee Charnas may have done something similar in her teen-girl-turned-werewolf story “Boobs”, but it’s been too long since I read it.