It's about a 10 - 15 minute walk from the slopes, but is the one where the photos of the frozen fountains are taken.
The Rila is right by the slopes, cross the road and you get to the Iglika, down a bit further and you get to the Samokov and further on and up a hill (I remember the coach having trouble getting up the hill at 2.30am) and you get to the Bor and Edelweiss.
You'd be best getting a cab in the evenings after partying and drinking the night away - best to be safe