riddle - "I'll make a stew of the lot of you"

I'll speak of my letters; though you might be confused:
So many to choose from; so many are used.

I sometimes have two, often three, at times four.
Dot if it helps you; for me it's a bore.

I'm known for my seven, my eight, different ways.
I can see that your eyes have developed a glaze!

I could speak of my children, let their letters be thine:
They have twelve, five and six; one has eight, one has nine.

Of the child with nine letters, to some it is known,
It sneakily has 'nother four of its own.

I've known some great heroes, with their fighting and fun.
Let me know when you've got it. I'm awake when you're done.

Hints:

Although I'm a noun, a person I'm not,
Nor am I a thing. What else have you got?

Another Hint: (for lover of rhyme @Brent Hackers)

When I get a visitor, and when he has been pluck'd
from a burg full of country mice, he'll surely be in trouble.

Another Hint:

A lady of mettle welcomes all to my scene
She's tall and she's French and she's def'nitely green.

Answer

Are you

New York City

I'll speak of my letters; though you might be confused: So many to choose from; so many are used.

New York is a city of many different ethnicities and languages.

I sometimes have two, often three, at times four.

NY is two letters and NYC is three.
'Times four' might be a sneaky reference to Times Square, or perhaps NY,NY or CoNY (City of New York).

Dot if it helps you; for me it's a bore.

These can also be written as N.Y. or N.Y.C. but are generally not.

I'm known for my seven, my eight, different ways.

"New York" has seven letters. "Big apple" has eight.

I can see that your eyes have developed a glaze!

"You've got New York eyes/ And it won't take much to fall in love with you"

I could speak of my children, let their letters be thine:
They have twelve, five and six; one has eight, one has nine.

New York has five boroughs. They are in order Staten Island (12), Bronx (5), Queens (6), Brooklyn (8), Manhattan (9)

Of the child with nine letters, to some it is known, It sneakily has 'nother four of its own.

Manhattan is home to "Alphabet City", avenues A, B, C and D (thanks to Chowzen)

I've known some great heroes, with their fighting and fun.

Lots of Marvel/DC comic book heroes originate from New York. Also, Gotham and Metropolis are synonymous with New York so include Batman and Superman. Many war heroes originate from New York as do the brave firefighters and other heroes of the 9/11 attacks.

Let me know when you've got it. I'm awake when you're done.

The city that never sleeps.

Hint 1

It's a place

Hint 2

I think there is a version of the Country mouse/Town mouse tale which puts Town Mouse in New York

Hint 3

Statue of Liberty

"I'll make a stew of the lot of you"

New York City is often referred to as "The Melting Pot"