I really like Za's, specifically the one on campus (there are two other Champaign locations). I find the food is always good and there is always a lunch or seasonal special e.g. summer on a Tuesday is $5 Create Your own Pasta/Pizza/Panini, free iced tea, and free chocolate strawberries. That's an entire meal for $5 and tax. Portions are always large (I usually pick 2: salad and pasta).
There is plenty of seating (just head upstairs if you don't like sitting close to people or have more than a party of 2). I love the plastic cups that you can take and bring back for cheeper drinks (think Starbucks or Duckin' Donuts without the expensive coffee) and the service is always friendly. Ordering can be a little confusing the first time (which sheet is for the pasta!?) but someone is happy to help you out and ask all the important questions (artichokes? do you like olives? do you want pasta? do you like cheese?). Overall, this places is fairly inexpensive, friendly, clean, and it's always open, even in those strange summer months when no one is around.