Me, for one (arriving morning of the first game). I know that a Boston-based group is also going but I don't know how many or who they are. I'm staying on after the tournament to take in some of the local sights and then go down to Dublin for a few days, and then on to Cork and Kerry, where I have relatives.
I also went in 2015 and had the time of my life. Notwithstanding the Thanksgiving Gala, the Titanic Museum should be on everyone's Must See list. It is stunning, and is built next to the slipways where Titanic and Olympic (her sister ship) were constructed. It also has a nice gift shop where you can pick up reproductions of china and glassware, among other things, used by the first-class passengers. And other nice and unusual gifts.
If you get to Dublin, be sure to stop at Madigan's Pub, on O'Connell St. near the GPO.