Usually I find I can get a seat I don't hate unless I am running so late that I am in the latter half of the 'B' group or anywhere in the 'C' group.

also have a better chance of not having to risk getting separated from your carry-on baggage because the plane's already full

One time I was traveling with a blind girl who had a guide dog and the boomer patrol had occupied all the bulkhead space. They seemed to think she should sit with a German Shepherd in her lap. Needless to say I aggressively advocated and reminded the flight crew that FAA regulations entitle persons with guide dogs to a bulkhead seat. Let me tell you, we got some stink eyes from the displaced boomers who didn't want to have to walk an extra six feet to the potty.