I made some sangria for a party - Spanish red, brandy, triple sec, peach schnapps, orange slices, lemon slices, strawberries, pineapple, generic tropical juice - and have accidentally left it out on the table while I was busy out dancing while under its influence. I know that as a rule, sangria that isn't on the table with some ice in it should be kept refrigerated, so my question is whether the leftovers are drinkable having been out for around 24 hours?
Grain alcohol (brandy, triple sec, peach schnapps) does not spoil while it's sitting in your liquor cabinet. A bottle of wine, even with the oxidation after it's opened, can be drank for more or less 36 hours after opening (eventually it becomes vinegar). The fruit would take time to decay, much longer than 24 hours.
Next time, eat the fruit.
I see that you already went ahead and finished off the Sangria, but in the future, I would probably recommend against it. Slicing the fruit exposes it to bacteria and between that and the juice you used it's always best to refrigerate perishable foods. I wouldn't be nearly as concerned as I would with leaving meat at room temperature, for example, but it always pays to be safe.
Sure, the final alcoholic degree is a key point in matter of conservation. Knowing what, how much and with which alcoholic degree, of the different beverages you put in your sangria, you should be able to grossly evaluate this final degree (consider fruits like their volume of non-alcoholic juice).