The most stylish, luxurious, and impressive.
The word 'swankiest' makes people think of fancy parties, expensive things, and feeling very good.
Examples:
The swankiest car at the show was a shiny red sports car.
She wore the swankiest dress to the party.
The swankiest hotel in town has a big pool and a fancy restaurant.
He thought his new shoes were the swankiest things in the world!
The swankiest house on the block has a golden door and a swimming pool on the roof.
The swankiest party I ever went to had a chocolate fountain and a live band.