I have a similar situation and as long as the venue is supplying the bartender I don't think there is any problem. I would suggest a few things...
1. go to EVITE and there is a drink calculator that is pretty helpful with figuring out how much to buy. I am airing on the side of caution and buying more than needed. Alcohol keeps so its better to be safe than run out!
2. You may end up saving money this way too, rather than being charged for your drinks.
3. Explain to your bartender any possible guests that may need "special treatment".
4. Alot of liquor stores offer discounts when you order large amounts. Check around and see what maybe the best deal.
Congrats and good luck!
try the Lafayette club across from the yorktowne hotel I am a dj and have done several events there and think its a pretty nice place and would be able to help you in your situation
Click on each tool to see a sample.