Bottle Sizes
There's a reason bars, clubs, and restaurants use a certain size of bottle and not the large half gallon jugs that everyone loves to show off in their #aboutlastnight instagram pictures. There's actually a few reasons. Listen up peeps because I'm about to drop some math on top of you.
1. 1.75L bottles (affectionately called handles) are 20% cheaper by volume than their 750ml counterparts (called fifths), but they have a 30% spill rate. This means that 30% of that bottle can and most likely will end up out of its designated target, either by spilling outside of the drink or spilling more than what is necessary inside the drink. If you're keeping count, that would mean you are actually losing 10% of that cost. See that extra $3-$5 you have on your night stand? Go ahead and paint it yellow and throw it away because that is roughly the same thing as buying handles.
2. I don't think it comes as a shock to anyone that handles are difficult to handle and pour out of. What you may not be considering is the labor cost of that. Imagine you're paying $40/hour for the bartender. Also, imagine the bartender can make 1 drink every 5 seconds, or 300 drinks in an hour. This of course applies to the simple vodka-soda/whiskey-coke type drinks, and not the creations we enchant you with ;) At $40/hour, your labor cost is a little over $0.13 per cocktail. Well with handles, our drink time can increase to 10 seconds or even 15, dividing the total amount of drinks we can pump out in an hour by 2 or 3, and increase the cost per cocktail by the same amount. If we make about 500 drinks in one night (which is very common), that's an increase of $65-$130. That $10 you saved by buying the handle doesn't look so glamorous now does it?
3. We've covered labor costs, but what about square foot costs? "What?! But we're not in the market for a townhouse!" Oh? But what about the bar. Imagine you rent a bar for $100, and that bar has about 15 square feet of usable space. That comes out to $6.67 per square foot. A handle carries the same amount of liquor as 2.33 fifths, and is about the size of 2-3 regular fifths. However, we really only need 1 fifth on the bar. As soon as that bottle runs dry, we replace it. Having the handle up there forces us to have the equivalent of 2-3 of the same bottle on the bar, sacrificing the space we would need for other ingredients. Using fifths would take that square foot cost down to $2.22-$3.33. Using handles keeps it about $6.67 per square foot. That's some expensive real estate.
4. Plain and simple? It looks ugly. The devil is in the details, and if you're looking for an amazing event with perfect presentation, I would stay away from large over-sized bottles. 750ml bottles are just a lot classier. Considering the amount of money that is spent on throwing an event, it would be silly to try and save a few bucks on presentation, especially on the bar, a focal point of any party.
Also, pouring those buckets of alcohol wreaks havoc on a bartender's arm joints. Unless you want bartenders to start including their medical expenses into their rates, I'd recommend choosing the most cost-efficient and attractive option.