Yeah, that caught my eye as well.
That, Quest for Glory 1, Pepper's, and The Pandora Directive are the only ones I haven't played on that list. I should give them all a shot.
Both Sherlock Holmes games (
Serrated Scalpel and
Rose Tattoo) from EA are good, lenghty adventure games. I think they sometime fail to recreate a true "Sherlock-ian" (?) atmosphere, but that's probably just me. Still, they are quite clearly better than Frogwares games.
QfG has to be played in its remade VGA form, since the original one is probably too archaic.
QfG IV is probably the best in the series.
Pepper's is a nice edutainment adventure. It's fun, enjoyable and if we had played it in our early teen years I could see it being an all time classic for everyone of us. Playing it as an adult could be quite a different experience (even though you could still learn something out of it). Still worth checking out, but it is what it is: a (great) adventure game for kids.
EcoQuest series is good too.
The Pandora Directive can be quirky and cheesy as you like, but it has a huge load of content. Of good content I mean. Lots of things to do, places to see, puzzles to solve and mysteries to unravel. Its interface looks dated at best (and it is), but it was incredible back in the day. One of the most complex (and not just annoyingly difficult) adventure games.