Vilnius is enough old town. So, we have a lot of interesting places for guests: castle of Gediminas, river Neris with 7 bridges (each bridge has name of colour), a lot of churches, two sinagoga's, one house of pray for muslim. For shopping is good place named by Akropolis or Ozas. For eating: many coffes and restaurants in old city or center.
About night life I can't say something, because I don't like night clubs. But I think, that Vilnius have enough amount of different kind nightclubs. So, welcome to Vilnius!