Things to See:

Royal Castle

Old Town Market

Łazienki Park & Palace

Wilanów Palace

Trakt Królewski (the Royal Route)

Restaurants:

U Fukiera

MOMU

Stary Dom

Bars:

Plan B

Mono Bar

Mazoweicka

Na Lato

Warszawa Powisle 

Rooftop Bars:

Level27

The View

Panorama Sky Bar