Out on the town- fun drinks in D.C.
PS7 is good, and defininately has the concoctions you mention (5-7 PM). another choice might be the Science Club (5-8 PM) on 19th near L NW (liitle booths for 2 up front if you get there early enough) appetizers don't live up to PS7's choices though. if the weather isn't completely disgusting, the courtyard at Poste is cool in a minimal, classic way (4-7 PM).
If you venture to PX in Old Town you'll find some of the finest crafted cocktails outside NYC. Mrs. Monkey had an amazing "Smoker's Delight" cocktail made from a smokey single malt, a single drop of distilled tobacco essence, and an "icecube" made from a piece of frozen honeycomb.
728 King St, Alexandria, VA 22314
If I were you and could go out in Alexandria instead, I would try to go to PX. The nice thing is all the drinks are so well crafted that your authentic concoction drinker will be really happy, on the other hand the drinks are so tasty that your lightweight friend won't feel bad because it is more of a slow sip and enjoy your drink environment because the drinks are so amazing, and you end up no matter what wanting to share. The drinks are not cheap I think like 10-13 per drink, but you will likely only have a couple and it is well worth it. You can also grab dinner before downstairs at Eammons Dublin fish and chips place which will balance off the price of the drinks, or the Pita House which is also pretty cheap, but good Middle Eastern.
PS7 is also good, and Oya has some interesting drinks too like their dark and stormy.
Rasika has a great drink menu, but the bar scene isn't as fun as PS7 and Oya, but the drinks are better.