Lugar

In school I was taught that instead of is en vez de. True enough, but en lugar de is also heard. ¿Y por qué en lugar de hacer eso, no llegas más temprano? Instead of doing that, why don't you just arrive earlier?

Put Someone in their Place

With expressions that translate directly between English and Spanish, the hard part is simply remembering that they're okay to use "as is" in Spanish. Put that woman in her place (cut her down to size) would be poner a esa mujer en su lugar.

Seat

Lugar is the usual word for a place to sit in an auditorium. ¿Hay lugares? Are there seats available? Or all they all occupied, taken, spoken for? Encontró unos súper lugares. He found us great seats in the movie theater / cinema. ¿Me apartas lugar? Save me a place?

Note that in these examples, we're talking about the spots available. To refer to the furniture itself, the thing you sit in in an auditorium, the word you want is butaca. Grandstands or bleachers would be gradas.