I would suggest you first find them in all of the census records you can. If you don't subscribe to Ancestry, you can find free records at www.familysearch.org
You can also search the social security death index there, which can give you death dates and places.
Obituaries can be a good way to find married names and where the children were living. There are various ways to find obits. First, I would recommend looking at the local genealogy society sites, and public library sites for the city they lived in - they often have obituary indexes, and will usually look them up for a small fee. If that doesn't work, you can put a request on the local message board, in this case for Milwaukee county.
Two good sites to use are the US Genweb site for the state and county you wanthttp://usgenweb.org/
has links for every state and county, and is a list of both free and paid links for research. That is how I found Andrew's obit. I saw that the site Newspaper Archive has Milwaukee newspapers online, so I searched that site. This site is a subscription site, but it is free to search, and everyone can read two articles a day for free. I just put in Stulo for the last name, then chose all cities in Wisconsin. If you get too many hits, you can add first names.
Here is Andrew's obit
Racine Journal Times, March 3, 1960, page 62
Stulo, Andrew John
9772 S. Chicago Ave.
Oak Creek, Wisconsin
Age 70, passed away March 1, 1960 in Trinity Memorial Hospital. Surviving are his wife, Mrs. Agnes Stulo; three daughters, Mrs. Frances Steglich, Mrs. Cecelia Ross, and Mrs. Agnes Balon;four sons, Joseph, Steve, Frank and Anthony; thirteen grandchildren; four great-grandchildren; three sons in law and three daughters in law. Funeral services will be held Friday March 4, at 8:30 A.M. in the Molthen Bell funeral home and at 9 AM in ST. Mary's Church. Interment will be in Holy Sepulcher Cemetery. Friends may call at the Molthen Bell funeral home, 700 Milwaukee Ave, South Milwaukee Wis. Thursday after 4 PM
I would recommend you post your query on the Milwaukee county board, since that is where they lived. Hope this helps!