Where to live?

Hi,
I am soon to be moving to Warsaw but would like some advice on the different districts. I would like to live right in the centre in Srodmiescie, but other places do seem to be obviously cheaper. I also have a potential job opportunity in Ursynow, so perhaps Mokotow might be a good in between. I'm just wondering really what it is like to live in each place. If I lived in Srodmiescie is there good transport links to everywhere else in Warsaw and how expensive is it? (If I am getting the bus everyday to Ursynow for example) Or if I lived in a different district like mokotow, wola or ochota is there still the same kind of things to do, nice restaurants and bars etc? We are a fairly young couple so would like to live somewhere that we can go out and meet new people.
Any help would be greatly appreciated! Thanks!