any advice on nice places/ walks around the city? (St. Petersburg)

Hello there, dear all :)
I have a couple of question regarding my very own city, if you don't mind?
Been away for quite a few years and lost a track of nice places around the city.
Any suggestions on a really good coffee place for a start?
Any vegetarian/ fresh food but no ovepriced restaurants?
On the other matter, if anyone is up to a nice chat/ walk somewhat from next week - would be really great.
Russians/ expats are welcome.
Am tempted to attent the party on June 14th, any good for a total stranger? :)
Hope am not asking too much for the fisrt time :)
Thanks a lot for any help here.
Daria