Are both sentences OK?
It is the last place I would check. (I mean I would never look there)
What will you get with that? and What will you have with that? (a waiter asks)

Question

Are both sentences OK?
It is the last place I would check. (I mean I would never look there)
What will you get with that?  and  What will you have with that? (a waiter asks)

Answer

It is the last place I would check. (I mean I would never look there)  Perfect

What will you get with that?  This is wrong, but you will find some younger people using "get" instead of "have".  They also use "Can I get a drink" in a bar.  To older people it means little and is slightly rude.  I'd avoid for a few years.

What will you have with that? Perfect