Here are a couple examples of similes from Act III of Romeo and Juliet.  In the first, Benvolio is explaining to the Prince in scene i how both Mercutio and Tybalt came to be killed.  As Benvolio explains, Romeo first tried to break up the fight between Tybalt and Mercutio, but when Romeo realized that Tybalt had killed Mercutio, he took up his sword:

But by and by comes back to Romeo,
Who had but newly entertain'd revenge,
And to 't they go like lightning, for, ere I
Could draw to part them, was stout Tybalt slain.

Benvolio compares the quickness of their fight's commencement and duration to lightning, which comes suddenly and unexpectedly, and just as quickly is gone.  Before Benvolio could take action to stop the fight, it was over, and Tybalt was dead.

The next simile is seen in Juliet's speech at the beginning of scene ii, as she waits eagerly for Romeo to arrive.  At this point, she has not yet heard the news of Tybalt's and Mercutio's deaths or of Romeo's banishment.  All she can think of is spending the night with Romeo, as she says:

O, I have bought the mansion of a love,
But not possess'd it, and, though I am sold,
Not yet enjoy'd: so tedious is this day
As is the night before some festival
To an impatient child that hath new robes
And may not wear them.

She is looking forward to being able to consummate her love with Romeo, and she compares the long, tedious hours of her waiting for him to the impatient waiting of a child anxious to wear new robes to a festival.