Jake's isn't open on Sunday's. It is worth the trip imho.
If you boys have never had soul food before, a visit to
Mr. Perkins (reviewed here) is real treat. Warm and friendly it makes great breakfast stop. 2nd choice would be
McBobs and like BB I would recommend the eggs and corned beef hash; it's spectacular. I'd check all suggestions for hours of operation but I think you and your boys would positively enjoy
Maria's Pizza if it's open. Inexpensive and with only soft drinks available it's a treat to the eyes and your stomach. Milwaukee has two places off the beaten path on a river, The
Horny Goat Brew Pub and
Barnacle Bud's. While both are taverns with food, children are OK and they are unusual; ditto with the
Safe House ( a spy themed restaurant). Of the 3, the food is best at
Barnacle Buds. Three Brothers is probably Milwaukee's most quaint and charming dining location but
Ilija's Place has far better Serbian food. Your other recs are great and I'll try to add some more. Will your sons try anything or do they prefer most 8 and 12 year old type foods?