I've run from 1.3-2" street tires on a MTB;didn't notice any difference in handling or stability,did notice a difference in comfort and weight. Skinnier tires will be lighter and help if you're climbing steep hills(or carrying the bike up stairs),wider tires will give a smoother ride.

okiride,what's your budget? What's more important,speed or comfort? Are your roads clean,or do you have to deal with glass/debris? For budget tires,I prefer Kenda Kwests or Serfas Drifters. For mid price,Schwalbe Big Apples(comfort) or Kojaks(speed). If you can afford them,I'm a big fan of Schwalbe Marathon Supremes;fairly light,excellent puncture protection,super grip,good ride,but expensive.