I, too, gave 4 weeks notice and I had some of the same reactions as you did. I was working only 2 days a week at the time, so my coworkers were already used to not seeing me in the office several days a week. I was working mainly on one project, so my goal was to complete it in the 9 days I was still going to be at the office.
I had some conversations with coworkers like those you had but very few attempts to get me to stay. It was no secret I was unhappy working there, especially ater I switched from working 3 days a week to 2 days a week 17 months earlier. There was no real support in my transitioning my other work to other coworkers besides my boss telling me which person(s) to send my stuff to.
My other big tasks in those last 4 weeks were filling out all the forms relating to my 401k account and company stock, all of which I was liquidating or rolling over. I also had to deal with COBRA and my last paycheck as well as a lengthy exit interview with HR to air my gripes.
But I got everything done including my big project, barely, and left quietly with my personal items. Nobody accompanied downstairs to the lobby so I had to remember to turn in my ID badge after I left the turnstiles. Then it was my long and awful commute for the last time, nearly putting me in tears on the walk home from the train....and FREEDOM!