This is the place you want to go in Scottsdale if you want expertly crafted cocktails that are so delicious that even your tiny-liver-having significant other will order more. They're that fantastic.
Citizen R&D is the "speakeasy" concept from the creators of Citizen Public House and with all the good food and drinks you can have downstairs, you should know that this is going to be the kind of place that really knocks it out of the park. You used to have to call from the back of the building to get in, but they've made things slightly less sketchy and all you have to do now is inquire at the host stand to find out details of how to get in.
Once you call to confirm space (no reservations allowed), you'll be directed to a door back behind the bathrooms and a secret stairwell that leads you up to the space. It's fairly sparsely decorated and no one is allowed to stand -- if there aren't seats, you can't come up. I recommend getting there earlier rather than later as you can often find seats at 6 or 7pm, but the later it goes the more busy it gets.
There's no backing on the seats, either (they're all benches), so if you have a bad back this could be a bit tough for you.
That said, getting in is worth it. They change the menu fairly regularly, but you can always count on delicious cocktails and enough tasty bar snacks to keep you from getting to faschnicka'd. I highly recommend the Black Blazer, which tastes basically like a toasted marshmallow but you're not going to go wrong with just about anything.
Small groups are best here -- more than six is probably pushing it, and four is ideal. And once you're done with drinks, go downstairs and have a full dinner. It makes for a great night out.