Is it, "The Andrews are coming for dinner"? Or is it, "The Andrewses are coming for dinner"?

The whole family
I am afraid I disagree with you Andros0. I believe that if you want to pluralize a last name ending in an "s" you should almost always add "-es", even if it sounds odd.
Assuming the family name is "Andrews" then "The Andrews are coming for dinner." is correct.

Pete Andrews = The Andrews

There are only a few instances when you add -es to the end of proper nouns to make them plural.
As far as I know, the only exceptions are s, x, ch, sh, or z.

Tom Jones = The Joneses
Karl Marx = The Marxes
Susan Church = The Churches

But, of course, there are always exceptions to the exceptions and Andrews is one of those. If the name end in s but it's pronounced like the letter z, then you don't add anything.
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 YoungCalifornian's reply was promoted to an answer.
Very well, your answer was "verified" so I'll concede the point. Emotion: smile

I did however find reference as to why I thought as I did.

"When a proper noun ends in an "s" with a hard "z" sound, we don't add any ending to form the plural: "The Chambers are coming to dinner" (not the Chamberses)[emphasis added]"

"Proper nouns that end in the hard "z" sound or the letter "s" have earned a reputation for being difficult to pluralize..." "The plural is formed on many names that end in "s" by adding -es or doing nothing."[emphasis added]
I checked out those web sites and I found the advice in both cases rather self-contradictory as well as contradicting each other.

The first states:

When a proper noun ends in an "s" with a hard "z" sound, we don't add any ending to form the plural: "The Chambers are coming to dinner" (not the Chamberses); "The Hodges used to live here" (not the Hodgeses). There are exceptions even to this: we say "The Joneses are coming over," and we'd probably write "The Stevenses are coming, too."

In other words, "Jones" is supposed to be an exception to the "don't-add-anything" rule. But no way of identifying exceptions is given. Where's the list of exceptions? one wonders.


The second is positively daft:

1. Determine if the ending s in the family last name holds the "s" sound or the "z" sound.
2. Add an -es to pluralize surnames that end in s with the "s" sound. "The Brasses are coming over (not the Brass's). "The Joneses are at the game (not the Jones').
3. Add no ending to surnames ending in the "z" sound. These names need no "s" at the end or apostrophes. "The Lodges are coming over" (not the Lodgeses). "The Stevens are at the game" (not the Stevenses).

Apparently the writer of this rule pronounces (see bold face print) Jones as "joe-nce", i.e., with an "s" sound at the end, almost rhyming with "don'ts" (as in "Dos and don'ts"). I didn't know anyone pronounced it like that.

Further, the first source seems to be all right with the plural Stevenses, but the second source says it must be Stevens.

That said, I personally have no objections to calling Chambers the plural of Chambers. It makes sense. It's certainly less awkward than Chamberses. And yet, it's not a rule I ever learned. Emotion: smile

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So which sounds better in the Stevens case? My last name is Stevens and it just sounds weird when I say Stevenses. Is there a right way and wrong way for my name?
It's your name. Do with it as you will.

My name ends in S. I will always, always add -es to make it plural.

If I were your sister, I'd say "All the Stevenses will be there." If you say "All the Stevens will be there" I won't hold it against you.