Challenger might actually be the only one to stay away. I can just see him going on a big lecture tour. Or maybe finding a new adventure to embark on. He's proved that he was right. Time to move on and conquer some other challenge.

Summerlee seems to be the only one who was genuinely fascinated by the place from a purely scientific point of view. He might go back just to do more "research" on all those spiffy plants.

Malone, of course, would go back for Veronica and perhaps as a companion to Summerlee. They all seem rather protective of the fellow. ;) And maybe he would have realized (like one of those bad cliches) that he'd rather live a little than just write about things.

Roxton would go back out of sheer boredom. I mean, how exciting can killing a lion be if you've already tested yourself against a T. Rex? Also, he'd have to make sure that Summerlee and Malone didn't get themselves lost and/or killed on the way back. ;)

Marguerite would return because she would have realized that she still doesn't fit well into the civilized world and the 1920s expectations of how a nice woman should behave. In TLW she got to shoot people just like the boys. Besides, who'd read all those cryptic inscriptions for them if she didn't go? ;)