Many times, the brothers and sisters of the deceased person will be listed with their place of residence and you can trace them IF you are unable to trace your grandparents. You should be able to determine facts about your grandparents and possibly great-grand parents. Also, record brothers and sisters of all these people if you can find them. Record any second marriages and the children of direct ancestors. I use family group sheets to record this info.
Place is important for searching the appropriate court house and newspapers for obituaries.
The reason you need to record the dates and places is to identify the correct individual later when you want to visit a library or court house. A good approach to genealogical research is to visit the county where your relatives lived and search in the historical section of the County Library and the County Court House. Be warned that many times, two or three individauls with the same name will be in the county. Many times accurate dates and places along with lists of sisters and brothers allows you to sort out the correct relative. See the following web sites for information on getting started in geneology.