Vancouver's a really poor city for adult clubs and dancing, especially for top 40 stuff, but as mentioned the Yale is good for blues/rock/jazz
If you're willing to step outside the top 40 box then there's a variety of latin venues that are great for dancing, and cater to all ages, but you have to like the music, and be willing to step in and do some salsa/cumbia/bachata/merengue/reggaeton. The Waldorf on a saturday, for example offers two bars with a salsa side and a reggaeton side. Both are fun, depending on the music you like.
Many of the cultural centres offer dancing of various types, and again have all ages crowds.
Singles dances and parties, even if you're not single, offer up modern music with a variety of age groups. The locations are moving targets though.They usually advertise, so check the local entertainment rags (the Straight, etc)
Most of these things give you the opportunity to go and meet single people, or just take your existing partner. The more latin venues in particular are very welcoming, and anybody you ask will dance with you, more or less, if they're available. What happens beyond the dancing is up to you and your level of game.