So if we can put people in hibernation for 1000 years, how will that effect them psychologically when they wake up and all their family and friends have been dead for 900+ years. Maybe earth society will have advance so much that people will see them as aliens. Maybe earth society will have advanced so much that their journey was merely scientific masturbation and blowing a lot of resources. What do people now remember from 1000 years ago?
I would assume you would know that goodbye is permanent if you were going into hibernation for 1000 years. Orphans might be a good source of crews especially if one generation of orphans adopt among the next and make up crews that way. Basically creating family to take along.
If we could achieve say 50% the speed of light we put a fair number of stars within a few decades trip. In that case I would go with hibernation in shifts of 6 months to a year.
In the movie Pandorum it was to be a 120 year trip with 5 teams doing two year duty rotations.