Horrible experience at gate. Would only fly Delta again if only carrier to my needed location. Upon time of check in, staff at gate, led my Maria L, at gate S5 on 3/15/13 at Sea-Tac airport for flight 182 Seattle to JFK, states repeatedly that "flight is full", there will be too many overhead bags, need volunteers to gate check overhead bags". The carrot offered is that passenger can board earlier (why would one need to board earlier if you don't need to find an overhead bin anyway?) Several people offer, most don't. Maria L then proceeds to go around the seating area picking out random bags and telling the customer they MUST check in their bag, like the Gestapo, several with small children, who complain bitterly. When people resist, she leads them over to the sizing bin, places their bag on top, and informs them that their bag is too big anyway. Then check in starts, and when zone 3 , my zone (the back) gets ready, she now states that all passengers MUST now check their bags. I resist, stating that several valuable gifts, which may be fragile, are in my bag. She tells me to take them out and check the bag. I ask her what am I supposed to do with these gifts, hold them on my lap for 5 hours?? She doesn't care. I tell her I would have packed differently if I had known this. She doesn't care, and insists that I check the bag, or I will hold up boarding the plane. She checks us in under duress. The kicker to the story?? We get to seats 30 d and f. When the plane door is about to close, my wife and I look up, and the overhead bins in our entire section are EMPTY!! My wife asks the stewardess why this happened, they deny any knowledge and state this is a gate decision. Maria L, from the gate, makes her final pass through the plane. We ask her why, she gives no answer. I ask for her last name and she states she is not required to give it to me, nor her badge number. My wife and I then are panic'd that our gifts are damaged the entire flight (they were not ). Who needs this? Seems to me this a result of bag charge fees, wherein everyone carries on more. Also emailed to Delta.