Vodka, Lime & Soda (or lemonade) is light enough, and there's a lot of liquid in there, thus you won't be making many trips back to the bar. Or else, Vodka and Orange/Cranberry/whatever will also go a long way. If you don't want to drink straight wine, ask for a spritzer - soda or lemonade. By diluting with mixers - fruit juice, soft drinks, whatever - it can be as 'light' as you like.