Serious Eats - seriouseats.com

For a really refreshing summer drink, forget about Rickeys and just
mix your favorite vodka with lots of ice, some lemon essence sparkling water and garnish with a lemon slice.
Now you're talking.

I cannot give a rational arguement for this, but I prefer Ketel One Martinis in warm weather and Crown Royal Manhattans in the winter.
If Crown Royal's unavailable CC suffices.
I order both drinks straight up with ice on the side so I get the Martini glass and ice when the drink gets too warm.
It's like rooting for the Yankees or the Mets. Being a New Yorker, I root for them both; and when they play each other I have a real problem.

I have no quibble with any of the other comments but - believe it or not - the Union Oyster House has absolutely wonderful clam chowder even though it's considered a "tourist attraction" because of its proximity to Faneuil Hall.
You're probably going to take your 10 year old to Faneuil Hall anyway (I took mine many times, and she's 30 these days) and we always stopped at Union for a bowl of chowdah.

My all-time favorite donuts were the whole wheat & powdered sugar ones at the old Chock Full 'O Nuts chain in NYC.
Otherwise I have to go with the Dunkin Donuts plain classic.
I remember when they came with little "handles" so you could really dunk them. Mmmm. But not as mmm as Chock Full 'O Nuts.

Grilled in butter, with sauerkraut and Coleman's mustard on a lightly toasted bun.

For pure reading enjoyment with the topic being "food", you can't beat:
Calvin "Bud" Trillin
Ruth Reichl
Jane & Michael Stern
Ed Levine
These are not in any order because I love reading them all.

I agree with Ed that the many (mainly Greek-owned) coffee shops in the City are the closest thing to an "authentic diner experience". I haven't had breakfast at either of the places Ed recommended, but since I live in the West Village (West Greenwich Village) my favorite places for breakfast are: The Village Den (corner of W 12th St & Greenwich Ave), The Bus Stop Cafe (corner of Hudson St & Bethune St) and, for a British breakfast experience, try Tea & Sympathy (Greenwich Ave bet. W12th & W13th Sts).
It's tiny, very cutsiewootsie and a lot of fun, but I think the only day they serve breakfast is Sunday.