i'm not too sure about just handing out a feat like that to 'all' vampires. given they have a strength bonus of +6, but half dragons have +8 and werebears have +16. what this boils down to is that a 'commoner' vampire is going to have a strength of 17 at best. while strong, that's not exactly 'pick someone up and hurl them against the wall 15 feet away' territory.
what you could feasibly do, is add the requirements of
snatch "Size huge or larger, or Strength 27 if smaller than Huge" but this presents its own pitfalls as PCs could easily get the required strength and then begin using your own tactics directly back at you.
perhaps looking into the Tome of Battle, as it has a school of martial philosophy called 'Setting Sun' that deals with throwing, tripping and hurling your opponents all over the battlefield. that way you could make it scary and cinematic, without overdoing it.
given that the snatch feat has the following to say about damage:
A flung creature travels 1d6 × 10 feet, and takes 1d6 points of damage per 10 feet traveled.
things could get pretty harsh for your players if all of a sudden, every Strength 17 through 21 Vampire is suddenly able to fling them upwards of 60 feet away.
furthermore, your PCs are going to want to eventually use the same abilities and if they meet the strength requirement, the game may start to get downright silly, especially once someone makes a monk/fighter who specializes in throwing every single challenge you pit them against 60 feet away
