I have less experience with BG1 than BG2 since I don't find myself itching to replay it as often. I did do a full playthrough of it five or so years ago, though. Not Enhanced Edition, though.

The encounter design really does feel aged and it can often be a case of the developers unfun/poor encounter design versus your attempts to cheese it. Line of sight/Fog of War abuse, stacking Skull Traps etc. There is also the tried and true method of blocking physical access to your team by a horde of summons and pelting away with arrows. Arrow of Dispelling is particularly powerful.