This is a revision of my original post, since I have more items to add and better information about some of the games.
It's too early for me to cast my wandering eye about, but my newfound taste for this kind of game has made me curious to find what other games exist with the same kind of style and gameplay. Basically, a party-based RPG with lots of quests, free exploration, and probably an isometric display. I do have to restrict things to a certain level of quality, at least graphic-wise, though. Turn-based or realtime with pause, and the option to speed things up are definite pluses. Here's a list of games like Baldur's Gate, with links to gameplay videos to serve as examples.
The ones closest in feel and gameplay to Baldur's Gate are of course the Icewind Dale games, though these don't have any party banter, since you have to create every character in your party. Second closest is Planescape: Torment. After that, there aren't any more Infinity Engine games, so what is "close" branches out further in several directions.
Dragon Age: Origins is the closest "modern" equivalent to the Baldur's Gate games that I know of, followed closely by Drakensang: The Dark Eye. Dragon Age: Origins is of course the game that got me into this cRPG genre in the first place, and although I don't actually play it in the isometric view, it does offer one. It's not necessary for my purposes that the games be D&D based, nor even fantasy, but it seems most of them on this list are.
The Temple of Elemental Evil is a turn-based D&D game, and like the Icewind Dale games, you have to create your whole party (or choose from stock characters), and there's no BG or DA:O-style party bantering. I've heard a lot about the horrible bugs in Temple of Elemental Evil, but I've also read that they've been fixed by official patches and fan mods, like what I found here: The Circle of Eight modpack. (Release notes for latest version as of this posting)
After those, the games by Interplay/Black Isle/Troika offer a somewhat different, but very enjoyable set of RPGs, those being Arcanum, Fallout 1 and 2, and Lionheart. The main difference here is that although you can have a party of NPCs (at least in the first 3; I'm not sure about Lionheart), you can't control them directly. You can access their inventory and equip them, but I find part of the game is preventing them from rushing into large groups of enemies. It's doable, though, and once you get the hang of it, the games are enjoyable.
I haven't played the other games in the list, so I can't say where Pool of Radiance fits in the lineup, nor where Eschalon and the Spiderweb games fit, though those are independent titles, and are graphically much more primitive than any of the others on this list. I did buy Eschalon: Book 2 just a few days ago, though, due to a nice sale on Steam, so I should be able to say something about it at some point.
Neverwinter Nights 2 is a new addition to this list. When I wrote this list originally, I had assumed that it followed the same party style as NWN1 (AI-controlled party members), but in fact the sequel gives you full control over your party. See my other coverage of this game for more details.
Close, but not quite:
- Neverwinter Nights 1
- Sacred 2: Fallen Angel
NWN has a lot of the right elements, but there's no real "party". You can hire "henchmen", but you can't control them directly as in the other games. It has a gigantic modding community, though, with thousands of adventure mods and some graphic mods which might actually make the ugly blocky 3D characters look decent.
Sacred 2 looks beautiful, but seems to be solo as well. I'm not quite sure where it falls in a scale between "hack & slash" and "RPG".
The Fallout games as well have a lot of the right elements, and I'll probably want to play them at some point, but as far as I can tell, you go the whole game solo (I'm speaking here of the first two Fallout games, of course, since I've already played and modded Fallout 3).
I'm generally not counting hack & slash games like Diablo or Torchlight, and Forgotten Realms: Demon Stone looks like it's in that style.
Games I haven't had time to research yet
These look promising, from what little I've seen of them:
I would welcome any additional pointers for other games that fit the criteria.