Are Middle Generations the Middle Children of Genealogy?

So we all know that the oldest child gets the full attention of its parents and the baby of the family gets spoiled by being the last in the house. Middle children tend to get neglected. While researching, I've noticed that it's relatively easy to find documentation for my seventeenth-century immigrants since they all were in New England where good recording keeping was the norm. I'm most interested in sources that can tell me something about their lives, beyond the basics of vital statistics. There were also many town histories and family genealogies published around the turn of the 20th century that document the stories of these immigrants. Recent generations benefit from the memories of living relatives. However, the middle generations are tough for me to track down. Does anyone else feel like this is the case? What are your favorite sources for these late 17th century to early 20th century ancestors?

The census is a good starting point to gather a bit of information about one's ancestors. Some of the census years have interesting tidbits that can help flesh out the story of their lives a bit. Some of my favorite things to look at are (some are supplemental questions that are only answered by a few on the page):

• 1860 & 1870 & 1880 - occupation, value of real & personal property, place of birth, literacy, citizenship, disability (deaf, dumb, blind, insane, idiotic, pauper, or convict). In 1880, the census takers started listing the relationship to the head of household. 
• 1890 - much of this census is lost but you might be able to find some of your family
• 1900 - age at marriage, number of children and number of living children (a good way to find children who are born and died before ever being recorded in a census). 
• 1910 - language spoken, industry (more detailed than occupation), employment status including number of weeks worked in 1909, home ownership, Civil War veteran
• 1920 - year of naturalization, mother tongue of person and parents
• 1930 - owns a radio, veteran and list which war or expedition
• 1940 - many more employment questions such as hours worked in a week, employed by a New Deal program, annual pay, 

The non-population schedules are interesting also. I have used the agricultural schedules to determine what my farmer ancestors were growing on their farms.

What's Growing on Your Farm, Great-Grandpa? - comparing two sides of my great-grandmother's family.
The Carter Farm in 1860 and 1880 - comparing two generations on the same farm
1860 Carter Farm - my first transcription of an agricultural census. Get a blank form and use it to see what is on each line.