To find out what stairs you can currently challenge someone in, first go to the Main Stairs Page, then click on "Show your stairs only" link. The ones in BOLD are ones you can make a challenge in. .
playBunny: I agree completely. I have also been wanting an additional set of "Normal Game" stairs with a decent time limit. (The only set of stairs with "Normal Game" are "Very Fast Fischer Stairs", which for ME personally are too fast! And the Standard Stairs take too long, since the games are played one after the other, instead of at the same time. Plus with so many draws, there isn't enough movement in them.)