\implies
($\implies$) is a marginally preferablemarginally preferable alternative to \Rightarrow
($\Rightarrow$) for implication.
There's also \iff
$\iff$ and \impliedby
$\impliedby$.
\to
($\to$) is preferable to \rightarrow
or \longrightarrow
for things like $f\colon A \to B$. The reverse is \gets
($\gets$).