It's interesting so many people are playing through the evil options. I keep meaning to, but when it comes time to make that decision I find that I can't. So I'm learning about lots of interesting things about branches of the story I haven't yet explored, making it likelier that I will at some point.
Though my memory of BGs 1 & 2 is pretty spotty after 20+ years, it's nice to see so many old characters referenced in the game. Though there are times when you'd expect certain mentions or encounters to provoke much stronger reactions than they do (or any reaction at all). Personally, I'm loving all the mentions of previous BG characters - or just canon D&D characters - because it rattles a few memories loose from the rafters. (Apropos of nothing, I found my BG2 CDs, but not BG1. I'm pretty sure BG1 contains a fold-out map of Faerun I'm hoping to frame... grrr!)
But the obvious stuff is obvious. I'll echo an earlier poster and say I'd love to see more discussions about the little nooks and crannies, the side quests, and the less-featured but still well-done characters because - any problems one might have with the central story aside - there are some interactions that appear fairly trivial at first, then turn out to have a profound impact on the story. That sort of threaded story-telling still amazes me. Yet I often miss out on things because I get too focused on what I'm already doing.
And also, how people balance their parties to maximize gameplay and roleplay at the same time. I see people talking about how the game is too easy. On Balanced, I don't find the game overly difficult, but I'm finding it sufficiently challenging. (For me, it's usually a matter of remembering to sufficiently prepare for the big ones, and just not playing cRPGs all that often). And I see a lot about specific character builds.
Also also, I haven't played pen-and-paper D&D since 3.5. So newer D&D classes like Warlock and Artificer (which would be a *great* class for BG3. just throwing that in there for gnome reason at all) are things I've only encountered in video games where I'm missing out on the underlying theory. I could go out and buy some 5th edition manuals, I suppose, but that seems like a stretch right now as I don't know anyone in RL who plays.
Finally, since we are wish-casting a bit, I would love to see a side-by-side leveling guide of all the classes. Like a spreadsheet where the columns are the classes and sub-classes, and the rows are filled with the leveling perks for each one. I figure there's a good chance someone has made one and thrown it up on the internet (though I haven't found it yet), so I'm hoping whoever makes it turns out not to be me (because I am lazy). I love muti-classing characters but keeping track of it all for multiple characters often eludes me (and so, lazy or not, if none such spreadsheet already exists, I'll probably end up making it.)
TL;dr - More discussion of the D&D/BGs 1&2 lore and continuing character progressions, more big deals made out of the little stuff, and maybe a little more of why people are choosing the party members they do.