What can you suggest in the way of cocktails that can be made ahead for parties? Which ones work? Which ones don't?
Batched drinks. It's the fancy term we use in cocktail-land to describe cocktails we make and chill before service. They're great at a party for all sorts of reasons. One of the cool things about making cocktails ahead is that you can chill them down in the freezer, which means you can serve them without ice. This means, though, that you need to stick with drinks that have enough alcohol in them that they don't freeze. Anything with juice, for instance, will end up solid, and not in a fun, El Bulli-esque way.
I'd look to the booze-on-booze classics: the Old Fashioned, Manhattans, the Negroni. If you plan on serving them iceless, dilute them with a little water to taste before you freeze them. Give the bottles a good hard shake before serving.
If you prefer something lighter and fresher, of course (such as the Bee's Knees, a mixture of gin, lemon, and honey; or the Rum Smash: dark rum, summer fruits and citrus, served with lots of mint and more fresh fruit to garnish), you can simply keep the mix in the fridge, and add ice as you go.
Best of all, batched drinks stay crisp and balanced all night, even if you don't.