Krapil's may be on the expensive side, if you're leaning that way I would probably choose Jack Gibbons instead
Bartolini's is pretty good, Ive never eaten there but I've used them for catering
Beggars in Oak Forest does a family style that is pretty good and they have a private room
Flossmoor Station Brewery has a banquet menu but no private room unless you can use the patio
Louisa's in Crestwood has a private room, they have a pizza that is a little different you can probably find a review
you could go really casual and have it at Hog Wild in Midlothian, great pork chops not sure if they serve liquor
Aurelio's Pizza in Homewood
Giordano's in Tinley Park