I'd also recommend the Monkey Island remakes... The new graphics are nice and still 2-D, moreover, they have the option to switch back to the original graphics and midi music for geezers like us wanting to have a little bit nostalgia.
Secondly I definitely recommend Day of the Tentacle. It was and still is my favourite for point and click adventure genre... Might be because I've spent an entire semester in my youth trying to solve the puzzles :) (My English was terrible back then) However, the graphics might be somewhat outdated, 320x240, if only they also remade it like MI series...