As a former server I try to tip fairly. I do expect decent service though. In Oregon a server is automatically taxed 8% of a bill.
I loved big groups. If you work hard you are usually tipped well because they understand what went into their service. I worked at Marie Callender's. Big groups usually meant meals and then pie and coffee. We did have a general rule about large groups paying an automatic gratuity. If there was a complaint (I usually reminded them before taking orders) I would make sure that management knew so they could remove it. In the times that happened I never had them tip less than what the automatic gratuity would have been.
Anjuli, recently separated mom to Bubbles, my 5.5 year old wild man, Squidge, my almost 3 year old daredevil, and Lou, my 7 month old newbie