I discovered BG2 two years ago as well, loved it. Then I moved on to its successor Neverwinter Nights, which is perhaps not a better game as such but still has sufficient advances over BG2 that it's hard to go back to the former afterwards (to say nothing of my shortlived attempt to play Baldur's Gate 1). Although recently I went back to BG2 and did like it again - the party dynamics and numerous good quests remain excellent, and some of its characters are iconic (Minsc and Irenicus come to mind).

The massive advantage of Neverwinter Nights is that, unlike BG2, it comes with an engine to create your own adventures, and a community that spent eight or so years making increasingly refined "modules" (and is still going on to some limited extent), meaning there are literally dozens of modules out there, some of them very extensive, that are as good or indeed considerably better than the original game (and hundreds that are at least somewhat enjoyable).

Other games that I've picked up and enjoyed include Age of Wonders (although again with the downside of continuously comparing to its sequel, which I'd owned for years), Heroes of Might and Magic III and IV (I'm inclined to say the former is the better game, though both can be fun), Disciples I (really not worth it if you've already played II, considering how small the differences between the two are). I also got the very highly praised Planescape Torment (same engine as BG2, but set in a darker, more mysterious and original universe), but never really got into that. Then at one point I made the mistake of buying Duke Nukem 3D, on the theory that I had enjoyed it way back when when playing it on a friend's computer - big mistake. I doubt I've played even thirty minutes, and I've very little desire to go back to it. Then not so long ago I got Age of Empires III, which seemed pretty good, but somehow didn't hold my interest for long, and that was only partially due to the way it pushed the limits on my computer (essentially, I could do everything as long as I didn't try to have naval combat on my screen - you'd be surprised how hard naval combat can be if you can only give instructions beforehand and afterwards and need to be far away while it's going on). And now finally, on someone's recommendation in another thread just this weekend, I bought Crusader Kings and have been enjoying it a lot so far.

So yeah, mixed record with GOG... but on the whole it's probably fair to say that between BG2, NWN and the two HoMMs, I got more than my money's worth for the total amount of money I spent at the site (AoE III and CK were from Steam, all the rest from GOG).