As a marriage and family therapist I am sometimes looked to for help in parenting. While I love being a parent - and I think I'm not that bad at it - and I definitly give good counseling on it; I'm not so sure that I always have universal advice for all parents; but unless your child is a mute I have one piece of advice that will save you hours of headache. I present to you ear protection.
After a 16 hour car ride to Kansas - and 8 hours of solid screaming - shortly after Israel was born we purchased two sets of these ear muffs before the ride home. That same year they proved useful on the extended road trips to: Lubbock, TX; Nauvoo, IL; Fairfax, VA; and Tallahassee, FL. They also proved useful on plane flights to Washington State and Utah that year, and a drive from Washington to British Columbia. Israel's first year of life included leaving the country and going through about 18 states.
Even day trips to the Gulf Coast put these parenting wonders to their test, and many a good night's sleep was preserved by keeping these muffs within arms-reach from my pillow. I'm thinking they should start selling these items in stores like "Babies 'R Us" or "Parents 'R Us" (hmm, that would be an interesting store).