I lived in Vancouver for around 15 years and I'm 34 now so I've got a pretty good vibe on its different night spots. My past year especially since I quit my job and didn't do much beyond play poker and go out. Probably too much, my wallet and health would argue.
Vancouver is nice that it has a very central street called Granville where many popular bars reside. During summer and the busy times of year the street becomes walking only. I've linked their yelp profiles for reference. Take what people say there with a grain of salt (a lot of haters); some places are shit on some nights though. Bars stay open until 2 or 3am (with the occasional 4am for some places on special holidays).
Your interest in hangouts, girls, and races may vary. Info is up to date up until around Oct 2012.
Most bars have an event promoter that posts parties they have on clubzone (
http://www.clubzone.com/h1/vancouver/nightlife.html)
Good to know what's happening at places on off-weekend days and where to avoid on weekends that will have huge cover and huge lines. Most weekend cover is between $15 and $20 for the busy clubs.
Some bars allow you to sign up for guest list on Clubzone. But it's sometimes only valid until 11 or 12, and sometimes you'll still have to pay cover (it's only "VIP line").
If you go out enough you'll probably meet different promoters and bartenders that you can hit up for guest list (they want you to come spend money there). I feel guilty about doing this sometimes when it's the only contact we've recently had and I'm asking for something, but I keep remdining myself that it benefits them if they're working and people come to the bar.
One problem with Vancouver that's especially prolific in the summer is massive lineups at nearly all the popular clubs. For both the VIP and the regular lineup. Often friends of bouncers/staff will just skip both. Table service skips all lines but cheap bottles are expensive ($120++). Past 11:30 at night until 1:30, you can pretty much forget about walking into any of the clubs such as (Library Square, Venue, Republic, Ceilis, Caprice, Roxy, sometimes Barcelona) unless you want to wait in line for 1-2+ hours. Over time, bouncer rapport game can help at some venues which can be HUGE or sometimes greasing $20 if done smoothly can skip the line but you'll still have to pay cover.
Monday:
Cellar (
http://www.yelp.ca/biz/the-cellar-nightclub-vancouver) I think still has different events on Monday that are very busy. In Winter they have apres ski events that people who go snowboarding etc. come to drink afterwards. There's not much open. Just people that might be at pubs.
Tuesday:
Go to Celebrities (
http://www.yelp.ca/biz/celebrities-night...ancouver). Line up can start getting long some days as early as 9:30 especially in summer. Mix of students and clubbers but some hot girls too. People hook up here but sometimes girls dancing in 4-packs aren't interested in talking to guys.
Cellar has live reggae which can be a good change sometimes but it wasn't packed.
Wed:
Starting to get a little busier. A few people at Cellar (DJ).
"Casa 967" at Caprice (
http://www.yelp.ca/biz/caprice-night-club-vancouver) is busy and packed with foreigners (usually student).
Ceili's (
http://www.yelp.ca/biz/ceilis-irish-pub-vancouver) is packed with people because of their dollar beer specials. Expect long lines, many drunk people, some slutty girls.
Thursday:
Cellar has a live band and is busy. Many foreigners again as promoters give out tickets for free near student housing. A lot of regulars come here each week.
Republic (
http://www.yelp.ca/biz/republic-vancouver) will have people coming and gonig through the night, but they will probably only be open upstairs.
Fri-Sat:
Everywhere is busy. My preferred spots to hang out because you can usually get in without waiting a long time in line, slightly older crowd, better music.
Joseph Richard (
http://www.yelp.ca/biz/joseph-richard-ni...-vancouver) less white crowd. But good ratios sometimes and guys usually stand around a lot holding their drinks.
Barcelona (
http://www.yelp.ca/biz/barcelona-ultra-lounge-vancouver) attractive crowd, decent ratios, reactions to being approached can range from friendly to ice princess.
Ginger 62 (
http://www.yelp.ca/biz/ginger-62-vancouver). My favorite club in Vancouver - great staff, good music, great crowd (least douchy of the Granville strip bars). Since it's near the end of the strip it gets a little less walk-in traffic of bro's and ho's. Gets busy but often is the right amount of full where you aren't shoulder to shoulder shuffling around. A lot of non-VIP seating compared to most Granville bars (usually none). Photobooth and semi-curtained booths for isolation. Take care of the bartenders and they'll take care of you.
Sometimes if I'm not into going down to the strip I might go check out Pint and Vinyl (closest Skytrain is Stadium Station).
Pint (
http://www.yelp.ca/biz/the-pint-public-house-vancouver) is a bar/pub that on Friday/Saturday that strangely has turned into a similar vibe/crowd as Yaletown Brewing Company (more on them later) - small dance floor, DJ booth, people standing around with drinks and mingling.
Vinyl (below Pint) (
http://www.yelp.ca/biz/vinyl-retro-dance...-vancouver) very young crowd, shorter lines, many UBC students. Top 40 / dance / 80s and 90s.
Sunday:
Republic has live reggae. I feel very white there sometimes. Worth checking out but line can get busy during peak hours.
Just next door is Roxy (
http://www.yelp.ca/biz/the-roxy-vancouver) playing live country music. If you're into that kind of thing. But girls like country, and you like girls, right? Crowd is a little oder and can approach the cougar age. Best way to descrive Roxy would be a sports/rock/pickup bar.