Summer Babies

I am expecting in mid-July and I'm curious as to what my newborn should wear. I've only had a winter baby so I am used to dressing a baby in layers. I live in Illinois and the summers can be warm and humid at times but we keep the air conditioning in the house around 68. Is it normal for the baby to wear long sleeve cotton sleepers of he or she is inside? Or should they be in a onesie? I'm more concerned about at night when I am.not checking on them constantly. What did other moms with summer babies do?