General greetings (Formal)
Hello!
How are you?
How are you doing?
How is everything?
How’s everything going?
How have you been keeping?
I trust that everything is well.
General greetings (Informal)
Hi.
What’s up?
Good to see you.
How are things (with you)?
How’s it going?
How’s life been treating you?
Greeting a person you haven’t seen for a long time (Formal)
It has been a long time.
It’s been too long.
What have you been up to all these years?
It’s always a pleasure to see you.
How long has it been?
I’m so happy to see you again.
Greeting a person you haven’t seen for a long time (Informal)
How come I never see you?
It’s been such a long time.
Long time no see.
Where have you been hiding?
It’s been ages since we last met.