I changed my usual approach (one "main game" and lots of smaller side games) and am playing quite a few bigger games at the moment:
Dark Souls Prepare to Die Edition - I'm not that much into "hard" games anymore (where you have to play long parts of the game again and again and again), but whenever I saw a picture of one of the awesome boss monsters I wanted to play this game. Now, after googling a bit, I've found many people saying that Dark Souls isn't THAT hard and that you just have to play a bit more defensive than in your usual Elder Scrolls RPG. Well... I took advantage of Steam's sale last weekend and got the game. I'm not too far into it yet, but up until now they're right. The game isn't too hard. You just have to keep in mind that every single enemy can kill you if you just stand there and take the blows. So keep your shield up, learn do dodge attacks (roll to a side), learn how to parry and counterattack and learn how to hit enemies quickly while they swing their weapons (wouldn't have thought that it's that complex!). If you do this, you won't die all the time. Boss fights are another thing, but the normal enemies are not that dangerous. At least that's what I'd say after 4 hours in the game.
The only negative thing so far: The game doesn't tell you a lot about its mechanics (Humanity, dying, reverse hollowing). Neither in game, nor in the manual -.- Devs shouldn't rely on gamers to create wikis. Writing a useful manual can't be that hard (and is better than wasting developmnent time for tutorial levels).
Dishonored - Not too far into the game yet (just got the gift from the Outsider), but I think I'll like this one. Finished the first part without killing anyone and it felt like a strange mix of Thief and Deus Ex :P There are even tranq darts! I think I'll stay on the 100% non-lethal stealth path. Thanks to a functional save system (auto save, quick save and manual saves), there are no "penalties" for failing.
The Incredible Adventures of Van Helsing - Seems to be a pretty good ARPG, but... Hell, there's NO manual AT ALL and the ingame tutorials are... useless. They explain the self-explanatory stuff and don't tell you anything about rage, skill power ups and the combo-stuff (and how this works with two skills equipped). Can't be too hard to write a manual. Seriously. I would've uninstalled the game if it wouldn't look like a decent ARPG. I don't want to read dozens of "y u so n00b" posts on Steam just to find an explanation of the basic game mechanics -.-
GTA IV The Ballad of Gay Tony - I semi-forced myself through the main game and started the expansions now. Haven't played The Lost yet, but Gay Tony is way better than the main game! That's exactly what GTA IV should've been. Weird missions (climb up a skyscraper, shooting a couple of helicopters down with explosive shotgun shells), good characters (Tony is great and Luis showed more personality in the first hour than Niko Bellic in the whole game) and more fun (dialogues with Armando and Henrique, Yusuf Amir cutscenes).
tl;dr - If you got GTA IV Complete Pack in a sale and stopped playing it because you didn't like the main game: Install Episodes from Liberty City and play The Ballad of Gay Tony! It's far better than the main game.
Sam & Max Hit the Road - Thanks again @ZFR ;) I'm playing it on my laptop 15-20 minutes every day right before I go to bed. I simply love this Bunn... uhm... rabbit-like thing (don't say the B-word!) ;)
Grandia II - One of my favorite JRPGs. I've played it to death already on my Playstation. It still has the best battle system for JRPGs.