For me, CodeMash is like a family reunion.
Even though the event has grown to 2500 attendees, I still look forward to seeing people that I've got to know at previous CodeMashes - many of them have been coming every year.
Sure, there are over 200 great sessions and I was proud to be asked to deliver one of them ("A Hitchhiker's Guide to Azure Mobile Apps"); and there are plenty of great workshops and I was pleased to help out at a couple of those presented by my colleagues; and there were sponsors (including Microsoft) happy to share information about their company and talk with potential customers or recruits or just about anyone; and there were numerous activities organized by volunteers, sponsors, and others, including cocktail parties, charity events, a record-breaking Pong game (the Guinness Book folks were there to confirm this), and a game room, and a jam session, and... well, you get the picture.
But, for me, the conversations with speakers and attendees are what make an event special. And CodeMash is even more special to me because I was attending for the 9th consecutive year. I still kick myself for declining an invitation to the first CodeMash. I learn so much from these conversations and there are so many experts to learn from at this event. I worked as a sponsor at the Microsoft booth for most of the event, so people were coming to me to talk. 
Highlights of the week included:
- A charity event organized by Microsoft in which attendees adapted toys so they could be used by special needs children. Over 100 participants adapted dozens of toys.
- A conversation with Mark Miller about UX design principles
- My own session, for which I received some positive feedback.
- The CodeMash Factory, where numerous people came to learn about and hack on IoT and other topics and build some amazing projects.
This was the 10th anniversary of CodeMash and it shows no signs of slowing down. It was an excellent way to kick off 2016.