Hi Marija :)
Nice to see a message from you. Rarely we have a visitor from Balkans here :)
Vilnius is nice, cosy and quite small city. We have lots of churches and quite big old town (if you like architecture), many parks and some nice caffes. In Vino, Tapo D'oro and Rene are the best if you like sitting outside, enjoying good vibe, nice food and vine. But they're Meditteranean style. If you want some national cuisine, you can try and ask in the city, because we have a lot of such caffes. But the best national food is in villages, so you won't get a good taste of it in town :)
Vilnius is cultural capital of europe this year, but government diminished the budgets a lot, so not many interesting events happening. If you like art, try www.culturelive.lt/en/main/ to see the list of events. Also www.djscene.lt/?lang=en if you like clubbing. We have quite many clubs, but none of them is internationally aclaimed. But you can check out Woo and Satta. They are always alive and laid back atmosphere there.
Best way to see the city is to take a walk through the old town and enjoy summer weather. Stop in some cosy small street cafee's, have a drink and continue on.
It's a pity I will be in Spain at the time. Otherwise I would try to find some time to show you the city ;)
If you will need any info or some urgent advice - you can call me 0037064045988.
Have a nice trip!