What happens to the dead? (Daniel 10-12)

I was reminded during today's reading of a question that was asked to me by a student one time about what happens to people when they die.  Do they go directly to heaven if they were believers, or is there a period of waiting?  In 12:2, Daniel refers to a resurrection that includes both the righteousness and the unrighteous, and it would be easy to draw the conclusion that people stay dead in the ground until Christ comes again and the resurrection takes place.  The problem with this line of thinking is what Jesus said to the thief on the cross: "today you will be with me in Paradise," (Luke 23:43).  After doing some research, I'm coming up empty handed as it comes to what Daniel was actually saying in those verses.  It does seem, however, that there are some who go directly to heaven upon bodily death, but I'm not certain as to who all that includes.