Hi
This is going to be totally unhelpful! I did my PhD at newcastle Uni and I think I went out in the town twice in three years. I also lived in Morpeth just outside of Newcastle for another year and went to Newcastle once. Pretty bad huh!
However, do take a visit to China town, which is fun to see and some great authentic chinese restaurants, and there are some nice older buildings in the town centre. Depending on which days you are there, night time there is always lots going on in the Bigg Market - if you like to see girls with next to no clothes on in all weather, getting really really drunk. The Waterside has some nice restaurants and bars by the River Tyne.
Apart from that it is a shopping mecca for cheap chain store shops in the malls. Word of warning, people do get very dressesd up there for no occasion.