I'm reliving my Planescape: Torment days (as in, the days when I had no life except for PS:T). As such, when I looked at PS:T and then at BGII, then at BGIII, I had an idea. No, not BGIII in the City of Doors, but why NOT have BGIII's "big bad enemies" be extraplanar creatures? The Rakshasa/Djinni theme could be explored a bit here, we had some of it in BGII (Trademeet) and in NWN:HotU (Djinn bottle). I'd like to see that fleshed out a bit more. And of course, there's the whole thing about Psionics, which was, I believe (could be wrong), not available at the time of development of BGII and was neglected by NWN. It adds an entire new direction that we could go in, and I really think it should be developed, too!
Although NWN was ok, I would prefer (and I can hear the howling already) to have BGIII be in the same isometric, top-down view of BGI and II. Besides keeping the tradition of the first two, I really don't think there's anything wrong with such a view, and we all know the saying about what ain't broken. It also gives the developers more time to do other things, like coming up with a truly enthralling storyline (I will worship them forever if it's anywhere close to PS:T's storyline), and perhaps make better casting animations and cooler (and more!) character portraits.
Other things that I wouldn't mind:
1: I know that it's
relatively easy to make additional portraits to your current listing of PC portraits, but if they made that even easier, I'd be even happier. Such a simple, easy-to-do thing like an Import Portrait button on the character creation screen could do wonders. If the imported portrait is then copied and pasted into the portraits folder, so that the next time you make a new character, the imported portrait is automatically available to you, even better (and that wouldn't be hard to do either). It saves the player valuable time, though, and makes them happy (well, at least it would make ME happy

).
2: I'm torn about the wilderness thing. While it's interesting that you could wander the wilderness (and if you ask me, if you're the type who likes alot of open, wilderness space where you could wander and occassionally stumble across interesting stuff and yet could get somewhere quickly if you had to, Arcanum is the game to look to for such a system: it's map is HUGE but the World map is extremely well done) I think that BGII's "sectioned" method makes travel faster and easier and far more convenient. You still get random encounters along the way to spice things up, but I don't see the point of wasting memory on alot of empty space. Still, easter eggs hidden deep in the open fields is an interesting and not altogether bad idea.
3: Getting rid of "instaTravel". While NWN's Stone/Ring/Gem/Chocholate Bar of Recall is interesting and convenient, I really feel that it's not ENTIRELY neccessary, and I liked BGII's transportation methods (namely, walking). Since this IS BGIII we should stick to what BGI and II had for transportation options. Perhaps, taking a nod to Morrowind, we could have fast routes between important hubs, but all in all, I really don't like the idea of the instaTravel because, while convenient, I find myself constantly looting everything and then instaTraveling back to sell it all, and then I don't get a chance to take in the storyline much.
4: As opposed to the "reputation" thing, I prefer more solid "rewards" for your actions. If you save a town, you should get more than just a reputation point, the town itself should like you more, and this should be readily apparent in the way the townsfolk talk to you and treat you.
5: Assassination should be possible. I know that this may really break some things in the way BG games are made, but it really seems to me that Hide/Backstab really doesn't seem to kill anything, just hurt the enemy a bit more than if you stabbed him/her upfront. If that is the case I'd rather just be a figher and pound them, because once you're out of the shadows, fine you damaged him but now you're dead meat. I think that they could remake backstab so that, at least at higher levels, if you attack from out of the shadows at somebody's back you ought to have a chance to kill the guy instantly. This will make sneaking alot more interesting, and perhaps to ensure balance, perhaps the chance for instant kill via backstab might be proportional to rogue/assassin/bard level, or something of that sort, and restrict it to only coming out of HIDING, not invisibility (so someone can't just get a few levels of wizard, just high enough to get the spell invisibility, then use that in conjunction with a dualed over rogue's levels to constantly pull off assassinations).
6: Persuade has been done very well over the course of RPG's in general. It's well covered; any decent RPG will have "pursuasion", but BGIII should also include intimidation (perhaps, at the beginning, you can use intimidation to prevent fights by scaring your opponents, or intimidating somebody to give you info), taunting (a la Morrowind, perhaps the "killing somebody without provocation is murder", also a la Morrowind, should be implemented too), and bluffing (lying, deceit, for instance somebody wants you to kill some other dude, but you find out that the other dude's a cool guy and you don't want to kill him, so you don't and let him go, your bluff skill will determine whether you can successfully lie to the quest giver that you DID kill him).