We always liked the Syberia series alot. Aside from all the Lucas Arts classics, we also (very) enjoyed playing the following 90/2000 (style) adventures:

• The Broken Sword series
• Broken Sword 2.5: The Return of the Templars | Download free version
• Runaway: A Road Adventure
• Runaway 2: The Dream of the Turtle
• Thimbleweed Park
• Edna & Harvey: The Breakout
• Edna & Harvey: Harvey’s New Eyes

Historic

• Flight of the Amazon Queen | Free at GOG
• Touché: The Adventures of the Fifth Musketeer
• Nelly Cootalot: The Fowl Fleet
• Ankh | Ankh: Heart of Osiris | Ankh: Battle of the Gods

Fantasy, fairy tales

• Discworld
• Discworld 2: Missing Presumed…!?
• Inherit the Earth
• The Simon the Sorcerer series - mainly part 1 and 2
• The Legend of Kyrandia
• The Legend of Kyrandia: Hand of Fate
• The Legend of Kyrandia: Malcolm’s Revenge
• The Book of Unwritten Tales
• The Book of Unwritten Tales 2
• The Book of Unwritten Tales: The Critter Chronicles
• The Whispered World

SciFi

• Machinarium
• Blade Runner
• Floyd - The Feeble Files
• Deponia | Chaos on Deponia | Goodbye Deponia | Deponia Doomsday
• Kaptain Brawe: A Brawe New World
• Beneath a Steel Sky | Free at GOG