I will mark this question as contemporary-latin because there are obviously not any precise classical equivalents of the titles implied by such English honorifics as Mr (Mister or Master), Mrs (Misses), or Miss.
This is somewhat related to another question about addressing superiors in Latin, but my question here is more practical: What is the best way of translating a sentence like "Mr. Smith Goes to Washington"?
Daniel Morgan's lexicon, section 754, gives options for Mister and Misses, but not Miss.
The options for Mister are based on suitable words for "knight," and are attested as follows:
(SEN. Ep. 3, 1: "si ... sic illum amicum vocasti quo modo omnes candidatos 'bonos viros' dicimus, quomodo obvios, si nomen non succurrit, 'dominos' salutamus, hac abierit) | 1652 TURS. 417, listing members of Parliament Charles I of England attempted to arrest in 1642: "Eques Arthur Haselrig, Domini Pym et Hampden")
Morgan does not provide suitable abbreviations, unfortunately.
In the notes to Superbia et Odium, his translation of Pride and Prejudice, Tom Cotton writes,
Latin has neither appropriate nouns nor convenient abbreviations (Mr, Mrs, etc) by which to indicate social status; to avoid the cumbersome repetition of Honestior, Matrona where Jane Austen has used the English abbreviations, I have devised the forms Hr and Mra. Elsewhere, I have adopted Hera, Domina, and Senior (Miss, Lady, Sir) to usages which are not strictly classical, but in which the meaning is unambiguous.
As I mentioned in a comment above, Terence Tunberg, who along with Milena Minkova runs the University of Kentucky Institute for Latin Studies, which (as far as I understand) uses Latin as its main language of spoken and written communication, uses Dominus for "Mr." and abbreviates it Dno. in the dative. If I learn more case abbreviations I'll update this answer.
I have seen dominus used for "Mr" in some comics translated to Latin. Analogously I would use domina for "Mrs". I don't have a good suggestion for "Miss", though. Perhaps the diminutive dominula is better than virgo or puella.
Therefore I would translate "Mr. Smith Goes to Washington" as Dominus Smith Vasitoniam it.
