I haven't played any of these yet, but they had good reviews when they came out. If you can overlook the old school graphics then you will most likely enjoy some of these games. These are the ones I picked up and plan to play at some point.
Deus Ex
http://www.gog.com/en/gamecard/deus_ex
Baldur's gate
http://www.gog.com/gamecard/baldurs_..._original_saga
Baldur's gate 2
http://www.gog.com/gamecard/baldurs_gate_2_complete
Icewind dale 2
http://www.gog.com/gamecard/icewind_dale_2
Planescape torment
http://www.gog.com/gamecard/planescape_torment
Alpha centauri
http://www.gog.com/gamecard/sid_meiers_alpha_centauri
This one I did play and enjoyed it alot but that was like 20 years ago!
Wing commander 3 heart of the tiger
http://www.gog.com/gamecard/wing_com...t_of_the_tiger
Coming soon
Legend of grimrock(release apr 11)
http://www.gog.com/gamecard/legend_of_grimrock