Horror Villain Wars R1: The Thing vs. Hannibal Lecter

The Thing's general nature tells me that we have no reason to believe it just wanted to go home. It's a conquering entity.
Yes, it builds a small saucer out of rover parts - but I think to escape another pending millennium of ice.
In the book this movie is based off of - "Who Goes There?" the thing is bent on escaping the ice to travel to civilization and infect the populace..

 

The Thing is anything but cheesy

 

That's one interpretation.
They don't specifically state its motive, but in 'escaping' the Norwegians and running directly to The Americans is it not simply seeking more opportunities to infect? The gun nor the grenade can truly kill the dog.
It's infectious nature IMO means the Thing is a hunter, not just a traveler. In this aspect The Thing and the Xenomorph are similar I'd say.

 

The prequel is revisionist so I'm not inclined to include that material.
But we already know from Alien that distress beacons aren't always what they are cracked up to be..

Motive for assimilation? Knowledge, malevolence and interplanetary domination is what I'm going with.
The Thing assimilates the host essentially killing it. Blair runs a computer analysis on the assimilation process and hypothesizes that it will take over the planet in a short period.
When The Thing assimilates a person it becomes them. They can think, speak interact exactly like the host did - without a hiccup. At this point there's no reason not to believe The Thing accrues all of their knowledge - including the knowledge that Antartica is not indicative of the rest of the planet.