[MoonBird]

I think the best example of the sequel being better than the original is Day Of The Tentacle, which you already mentioned. But there are others as well:

Black Mirror 2 and 3 were better than the original, which is quite impressive, because I thought Black Mirror was so great, there was a little room for improvement, but Cranberry really did it!

I think Discworld II was slightly better than it's predecessor in some ways. Definitely not worse, that's for sure.

Then there is the Legend Of Kyrandia series, and I think it's rather crystal clear that Hand Of Fate was a big improvement over book 1.

As the opposite side of coin... there's much more examples of the sequels that were absolutely worse than original. Still Life 2 is perfect example of that. Also the Runaway-series I think sinked statically from 1 to 3. Yes, 3 was worst of them IMO.