At some point in your life, you need to re-read Twain. Melville can survive on one reading if you know what to highlight...but Twain is a great misleader of youth and must needs a perusal in middle age to see if he holds up.
After all, he rules the high schools of this great Republic....Huck Finn in particular is assigned reading all over the nation.
tom Sawyer is still a god-damned funny book, you really do get the impression of Tom at loose ends in what amounts to a barbarian camp in pre-civil war Missouri. Riddled with superstition, poisoned by slavery, debased by revealed religion the mythical town of Saint Petersburg is the last stop before the wasteland.
And there in the middle of the street, stands Tom Sawyer that boyish American Sigfried, bound and determined to wring all the diversion he can out of a deadbeat hayseed village.
Mostly he succeeds in between the inevitable beatings from his school-master, his aunt, the local clergy etc etc.
Tom like Clark Kent and the aforementioned Sigfried is an orphan, instead of being raised by woodland elves and dwarves, he has to put up with his Aunt Polly's lackluster supervision, mostly he pays it lip service and goes on his merry way as much as possible.
Still and all that, you get the impression for all his adventures real and imagined, nothing much will come of Tom. Defiant though he is, in the end, time adulthood, revealed religion and superstition will combine to make a dreary clod of him. He has peaked in boyhood.
Huck Finn on the other hand shows growth potential thru-out the nominal sequel. Originally he is a somewhat cowardly sidekick for Tom, by the time though Huck escapes his tyrannical drunken father and takes to the river with Jim the runaway slave he is a veritable American Ulysses in fine fettle and ready for any deed.
Tom is a pretty interesting kid, but he'll grow up to be a fairly nondescript man, Huck on the other hand comes from the American frontier wasteland and is one his way to being a adult and even a hero.
What unites the books is the paucity of worthwhile adults, in Tom Sawyer they are all scolds and fools in Huck Finn they are all crooks and even killers.
No wonder Huck flees down the river, he is shedding off civilization...he even gives up any pretense that Jim might be inferior to him and openly conspires to deliver the negro to freedom...purely out of friendship and a heroic devotion to a higher duty.
The books are both wonderful in short....they survive a middle aged re-reading nicely. To Mark Twain western literature in the 19th century owes a lot, he broke the hold of ponderous empire worshipping English Prose with it's doorstop dimensions and gaseous rhetoric of sheer nullity. Twain's dialogue crackles and his characters burst thru the page, everyone else at the time was writing by the yard, Twain wrote for the ages.