When it comes to the Sarlacc while I'm not too keen on the Little Shop Of Horrors stylings of the SE version I think George did have a point about it just sitting there.
Perhaps when the barge arrives at the Pit Of Carkoon there is just a pit covered with sand.
As the skiff approaches the pit the Sarlacc pushes up out of the sand and tries to reach for it like the giant squid in Twenty Thousand Leagues Under the Sea.
It's still anchored to the desert floor (so not as mobile as the sand worms in Dune) but it can move about a bit, especially when the skiff gets damaged (it would be fun if it pulled people off the wrecked skiff with even longer tentacles in a more convincing manner).
Star Wars has too many Venus Flytrap style opportunist feeders (see the great space slug debate on the ESB:R thread) and I'm sure we could keep the frankly obscene design ethic of the OUT Sarlacc but pimp up it's action potential.