@Sounds,
Not so much for searching, but for sorting, I use genre mostly.
For example, I've got the crowd captivated with a song, but not sure where to go with the mix, but I know the song falls into a particular genre I've established and tagged.
Rather than scroll through endless songs, if I did my genre homework up front, I can quickly scroll through a small list of songs that might match up well with what they're digging at the moment.
I don't look at BPM or many other factors -- I try to take the song in play into context, using the genre, lyrics, and the way the crowd reacts to certain things within the song. I equate genre with the "feeling" of the song. For example... Margaritaville == beach party. What else fits in that genre -- maybe Kokomo and other songs from the Cocktail soundtrack, La Isla Bonita, Uncle John From Jamaica, etc.
I try my best, to put myself into the crowds head at the moment, and genre works best for me