What I would/will do? First of all - say goodbye to all people I know. If we were in bad terms for whatever reasons - I would try to say my farewell knowing I apologised for what I did and forgive for what was done to me. I'd like to have clean head from human affairs on my last breath.
Then - I'll go to reconcile with God. Maybe first time in my life truly and honestly. I'm a believer in Jesus Christ so this will be best and last time for it.
After that - I would spent all the left time on being with my dearest one. Talk to them, hug them, take tons of photos. And also - this is what I plan for some time - write a long letter to each of my dearest, telling them how much I love them, how much I received from them, how much they mean to me, how wonderful people they are in my eyes.
And when the time comes, when it'll be the last breath - I really hope God will came for my soul and we all meet once again.