Good mixed alcoholic drinks for two?

My boyfriend and I are getting together at his house tomorrow, we'll have dinner there and enjoy the fireworks from his back yard, we usually drink beer when we want to have some alcohol, but tomorrow I feel like having something different I want to impress him with a yummy alcoholic mixed drink. The thing is we don't want to get completely drunk because he'll be driving me back to my place at around midnight since we have work the next morning. I dont want to buy a large bottle of anything, just something that will makes tipsy and feel relaxed and lightened. Any ideas of what i should get?