A man is free if he is free.
A tautology of the form: P→P
You can't know anything unless you know something.
Suppose Kx means 'x is a known proposition' and we're just talking about everything, this says: (∀x¬Kx ∨ ∃xKx) which with quantifiers exchanged amounts to (¬∃xKx ∨ ∃xKx) A tautology.
I wouldn't be here if I hadn't arrived.
A tautology like the first, without mincing the meaning too badly, this says: (¬P→¬P)
(it might have some tensed/modal meaning too, but then it won't be a tautology.
Business is business.
Kind of a weird thing to consider.
It might mean P therefore P.
It might mean:
∀x(Bx→(x=x)) (where B means 'x is business' this says if anything is business it is identical to itself.)
It might mean: ∀x(Bx→Bx) with a meaning analogous to the first tautology again.
The problem here is that we're considering an idiomatic expression, something like an exclamation rather than a statement (the truth-evaluable stuff of logic.) Then it's not a tautology.
Boys will be boys.
Again an idiom, or something. Strictly parsed it might be like, where Bx means 'x is a boy', t and t' are times, and x<y is a relation and means 'x is later than y' and Lxy is a relation and means 'x is located at y', and finally we're talking about everything:
∀x∀y(x=t ∧ By ∧ Lyt → ∃z(z=t' ∧ t'<t ∧ Lyz))
Or something funky like that, without modifying the logic too much. Not a tautology in quantified predicate logic. In tense logic it's not good either, basically: p→F(p) (Being a boy implies future boyhood) Kind of confusing overall.
"A rose is a rose is a rose." (Gertrude Stein)
Where Rx means 'x is a rose', and we're talking about everything:
∃x∃y∃z(Rx ∧ Ry ∧ Rz ∧ x=y ∧ y=z)
Not a tautology. Charitably we might wonder if it means everything is identical to itself, in which case it is a tautology, one of the laws of thought.
"Become who you are." (Friedrich Nietzsche)
An imperative, not a truth evaluable statement.
Final thoughts: Forgetting about the little semantics I've done for the logical expressions, just look at the expressions here and think: is there an interpretation (and domain) for these symbols that could make them false? A tautology's truth will come from the fixed logical meanings of the connectives or quantifiers or identity. Hence logical truth.