This is actually a tougher question than you might think.
For a guy like me who's in his 30s, the weekends are worse for meeting random women than the weekdays. I find it's easier for a 30s guy like me to meet random women when we're just out running errands.
And since most of my friends are married with kids, I'd have to roll solo.
I honestly don't know where men can find quality, decent women on the weekends.
Friday and Saturday nights at the bars is one of the worst options for meeting women that might amount to anything more than a one night stand. There are even better options than Fri/Sat nights at the bars for one nights stands and casual sex. I can think of better nightlife plays.
There is a ton of hype around the increase in childlessness in the Millennial generation.
@Xenom0rph is a 30 something Millennial. I'm also there too. The hype rarely matches the reality though. The reality is that although there has been an increase in childlessness and unmarried marital status into one's 30s as Millennials, the typical Millennial in their 30s is in some sort of committed relationship at any given time. Unattached and marginally attached men in their 30s (men who typically have shorter term relationships) are often at the fringes of social circles. Social circles, even for Millennials in their 30s, are dominated by established couples.
Seduction at bars/clubs is more based upon going out in groups more so than rolling solo. I have rolled solo to bars many times and done approaches. Women have never outwardly questioned me for it, but it does feel a bit out of place to do it. Being Dark Triad, especially psychopathic, can help in managing those feelings.
You could do plenty of non-bar approaching on the weekends at city parks, walking/hiking paths, gyms/fitness classes, grocery stores, and malls/other retail. It's much easier to find a woman solo in those settings. Those settings are also available during the week as well.
You might need to do some bullshiit, weak social circle type thing like a co-ed sports league for getting your dicck wet, though it can be tough to swoop in and do that.
Whether you go to bars or clubs, you'll probably notice that women roll in groups with their male friends or boyfriends, which means you can't make a move without some conflict popping off.
Over the years dating all the way to the 2000s, I have tended to see women rolling in groups with their female friends more than ones with their male friends.
All the quality women are already in relationships. If the girl is so great why would she be single and going out to a bar/nightclub?
Even a quality woman can find herself single at some point. She is more likely to find a new man via her set of social acquaintances than any other option out there. Daygame is a good hack for men as well. The bottom of the barrel is swipe apps. Bars/nightclubs are a little bit above that. Almost all women who find themselves single at some point will find themselves going to a bar/nightclub with their female friends/acquaintances if they don't have an extensive social circle. It's possible to find something decent via the bars/nightclubs but it'd take a lot of work. If you want an extended relationship with a woman, the best venues for finding that are social circle, organized social groups (like a co-ed sports league, not anything off of Meetup.com), or some sort of non-bar approaching.