here y'all go:
"May I end a sentence with a preposition?"
Contrary to popular opinion, no rule states that it is incorrect to end a sentence with a preposition. A principle of style, however, declares that one should not end a sentence with a preposition when one has a graceful alternative. As Theodore M. Bernstein says in The Careful Writer (Atheneum: 1968), "It is well to consider that a sentence ending with a preposition is sometimes clumsy, often weak." But Bernstein adds that "a preposition can itself provide strength at the end of a sentence." "This occurs," he says, "when the preposition carries real import and the verb has a rather low charge; in such instances heavy stress . . . falls on the preposition, and idiom declares that it appear at the end."
Bernstein's examples prove the point. How else are we to say, "He didn't know what he was getting into," "I found this tool, but I don't know what it is used for," or "I didn't know what it was all about"? Consider, he says, Shakespeare's "We are such stuff as dreams are made on" and such expressions as: "That is something to guard against," "He is someone you can count on," and "You don't know what I have been through." Bernstein wryly suggests that anyone who calls such expressions wrong will find that he or she "hasn't a leg on which to stand."
It's interesting to note the origin of this faux rule about prepositions -- and the one about split infinitives. When English grammar texts were in their early stages, about 300 years ago, the grammarians were far too enamored with Latin and its grammar.
For some inexplicable reason, they founded these rules on what they observed in Latin grammar: Latin did not end sentences with prepositions [primarily because most Latin prepositions were imbedded in the ablative or dative endings of nouns and pronouns] -- and Latin did not split infinitives [because Latin infinitives consisted of only one word, not two words as in English].
Based on this totally bogus reasoning, they tried to impose those two "rules" -- and we are still dealing with the problem today. As you pointed out -- the real rule for both is "whatever seems to sound the best" or "what sounds the least awkward."
Oh, well -- I still don't understand why grammarians cannot fill stadiums with paying customers to listen to them discuss these things. Life's not fair!
M