I wanted to know if you'll join us for lunch or not.

"I am delighted that you could join me for lunch."

I should like it if you would join us for lunch.

Oh, my father is going to join us for lunch.

"When you've finished your work, I'd like you to join me for lunch today."

Without looking up he said, 'You two join us for lunch?

Why don't you join us for lunch on the terrace, Mark?

Recently I asked him to join me again for lunch.

"I thought you might like to join me for lunch."

When you can, join them for lunch or a cup of coffee.