Hmmmm....Well, sex/city theme maybe cosmopolitans or long island iced teas. Those are generally quite strong for a 21 year old, unless you already have plenty of drinking experience. Here is a good recipe that I generally make for women who don't drink often and come into my bar. 1 oz. Amaretto 1 oz. Melon Liqueur (green, not watermelon) and add cranberry juice. You won't taste the alcohol much. It tastes like Kool-Aid. They have a rather low alcohol content, but nice for social drinking, however still maintain a responsible environment...lol. If too weak, just add Vodka to your liking. They look refreshing especially with an orange/cherry flag garnish. Maybe some of those 8 inch glow sticks for stirrers. That sometimes is cool. I would skip the premade cocktails. I can direct you how to EXACTLY make anything that you want to serve. Another good girly drink is a 'Baybreeze', which is Vodka, fill w/ 1/2 cranberry, 1/2 pineapple. I've been a bartender for over 10 years and work in the French Quarter in New Orleans. Email me and I can give you any instructions that you may need.