Yeah the morning after the party I touched bases with Lae'zel and after hearing her what she said about the other companion she decided to spend the night was amazing honestly. I love her to bits and I hope she doesn't change in that regard because I just love there being this character in my party that's so free and to the point about that stuff.
In Astarion's case, I have a gut feeling he'll be able to steer a certain way down the line just given some of his dialogue and facial expressions but I'm also just being hopeful. I feel like he's a special case because he's absolutely having the time of his life with this newfound freedom the tadpole is giving him, so it feels natural for him to want that sort of intimacy and to be fluid with his partners. Although, if you turn him down he doesn't go to anyone else that night so there's that to think on. (He says it himself that Gale's blood tastes like bile and I can't imagine him wanting to sleep with a Monster Hunter like Wyll. Lae'zel would literally kill him and I'm not too sure and I'm not too sure about Shadowheart.) Anyways, I get so many mixed signals from him. He's very flirtatious and comes to you at the party asking if you would be willing to indulge him in having some fun, but if you tell him essentially, "I'm just here for the transaction" there's some disappointment in his response. He also has all of these moments where he 's put in these vulnerable states where we're allowed to console him that make me think just maybe there might be a possibility for something more. Who knows honestly.
Lae'zel rubs me wrong, personally, but I at least respect her honesty. She's a terrible liar. But also just terrible lol. It seems Lae'zel always bangs someone at the party. In the run where I romanced Shadowheart she banged Astarion who she described as something like "skilled and enthusiastic." Which I found amusing. She still seems to hate him though and takes great glee in betraying him to the hunter. Regarding Wyll, Astarion mentions that, of the party members, he's most interested in Wyll's blood. Something exciting about a dangerous conquest I think.
I have very similar hopes for him. Maybe we can dream that Larian will see these types of posts and be kind to us. :') Unlikely, but one can dream. The thing about Astarion is that he's very adept at persuasion and deceit. I think these qualities are really well written into his dialogue and your responses work as if he's passed his own persuasion checks on us. It's a really interesting concept. So his nature is duplicitous, but we get these brief flashes of something genuine when he speaks of Cazador and his trauma. He's got these insane barriers he's erected to protect himself and you can see moments where he reinforces these barriers between himself and the player. If done right, this is one of my *favorite* types of romances--if he can eventually let the right one in. (Let the right one in? Get it..? Vampire film...? I'll see myself out.) I could easily see him being an option for a poli romance and I'm fine with it if that's an option but unless there's also an option for something exclusive...

It won't be for me. *fingers crossed*
Yeah - I also saw a pretty big change in expression for Astarion if you choose the "I just want fun, that's it" as opposed to the first option and thought that was interesting. I'm not sure whether that's intended or not, but I'd think it is? The facial expressions in this game so far are very on point, imo.
I was also thinking along the lines that it'd make sense for him to not want to commit to anyone, given that he's just reclaimed his freedom, but he does also ask people if they "have loves waiting for them" in Baldur's Gate during a banter, which might mean the concept isn't unthinkable to him? I'm not sure.
Also, from what I've seen, the "city is full of sweethearts" banter can also be him answering "no sweethearts, no. I prefer them savoury" to which Shadowheart replies "this is what I get for trying to strike up conversation". I don't even know why this changes, though, but I thought it was interesting that they put it in there.
I'm really excited to see how Gale's romance plays out, too, although it's a bit too fast paced for my liking, since (as it is now, at least) you have to get the weave scene pretty early on to trigger the party one, and out of all the romances, his feels the most committed despite him having feelings for someone else. Which means you kind of create this romantic bond with him early on, as opposed to the others, who might throw in a flirty line or two but nothing else until the party happens (maybe Wyll has another scene too, but he's so buggy for me, I can never seem to trigger them). I definitely like his romance so far, but I'd wish they'd spread his scenes out a bit more, I guess.
I'll need to select that option again. I only picked it once and didn't notice a particular change from him but that's interesting.
I feel like all the romances happen too quickly--even the casual hookups. I'd like some more specific flirt options before the party. Really, none of the companions flirt enough with the pc but they flirt a lot which each other. This bothers me--I love flirting! Hell, I flirt constantly with my friends with no romantic intent. It's just fun. Astarion gives the most flirty options which may be part of why I prefer him so far. But there just isn't enough relationship building overall--romantic and otherwise. Gale flirts with Shadowheart right off the bat but not the pc, who he treats the same no matter what. PC needs more love, Larian.