So, I’ve somehow managed to snag a stool at a crowded bar on St. Party’s Day. Clearly, selling my soul to Mephistopheles/the Feds/Skald is paying off.
But it was the last stool, and there are women standing behind me. Is it rude for me to keep my seat?
You can always offer them your lap…
Why would it be rude?
Any woman ‘old-fashioned’ enough to expect a man to give up his seat for her wouldn’t be in a bar alone anyway. Stay put.
Unless you want to score points. 
<—female…old enough to not be TOO surprised if a man offers his seat, but young enough to not accept it unless I’m stupid enough to wear high heels in a crowded bar.
Women have an ability to stand that equals that of men.
As a feminist, I say keep your seat. As a southerner, I say get yo butt up and let the ladies sit, what’s wrong with you! So I voted Eh. I guess it really depends on where you live. Those hussies in New York City probably don’t expect or want you to get up for them. In small-town Alabama, you best respect the ladies, son.
If they’re friends and wearing very high heels, go ahead and offer. If they’re strangers, or friends in flats, no need. Just MHO.
I voted other.
Are you there to meet women or are you there to drink?
I only offer my seat if the women in question is visibly in need of a seat. (Disability, elderly, etc) I use this general principle in nearly all situations.
Unless she’s heavily pregnant or obviously infirm, keep your butt on your seat.
Hell yeah. Move your blooming arse!
Offer your seat to someone you’d like to shag.
In theory. In practice, I have terrible balance! 
But yes, men, keep your seat. I’m a delicate fucking flower, true, but I think I’ll survive it.
It’s more complicated than just sit vs stand being polite or not. Most of the time women are in a loose group of some kind, and while they may take your seat, if offered, to be more comfortable while they stand around, if they cannot get seats for their friends to perch around them they will often very shortly flit off like a butterfly to a table or elsewhere, and your precious seat will be taken by a young guy who is perfectly capable of standing.
Are you trying to get laid, or trying to get drunk?
I agree. I might also throw it in if they are acting like they are searching desperately for a seat, even if they don’t look like they need it. You never know.
I also don’t believe that giving a woman a seat does anything good for your chances to get with her in this situation. If she takes your seat, she’s likely going to turn away from you and face the bar, and sticking around trying to talk to her will be awkward with her back towards you. More often than not, she’s not going to turn back around, and you’ll just be out of a seat.
And that’s assuming some other person doesn’t take your seat before she has a chance. The only real reason to give up your seat is if you plan to actually go and talk to her rather than giving her your seat.
If she wanted the stool she shoulda got to the bar earlier. And why were you posting when you should have been drinking?
If I were alone I would likely offer my seat to a woman. Well, maybe not. If I were alone in a bar, I probably went there with a book and just wanted to read my book and drink a beer. But in your situation, knowing me I would offer.
If I were with people - well, I’m with people.
And by that exact principle, it should be offered to a man in those conditions. It’s a matter of need, not physical gender (or whatever the correct term is these days).
Mostly this. But if you’re one of those guys who gets all hung up on chivalry, a good compromise would be limiting your seat sacrifices to women in the group you’re with, rather than any woman in the bar.
And if you’re not with a group, then screw it. Siddown.