In his novel 2312, science fiction writer Kim Stanley Robinson describes using hollowed-out asteroids, roughly 9 kilometers in length as "terrariums" powered by engines and containing fully self-sufficient towns and thousands of occupants inside them for the real long hauls.
Makes perfect sense. The bigger the ship and the more passengers the better.
Today we can only send tiny crews of very highly trained people. If you can send 50,000 people you could send your everyman as long as you make sure you have the skills needed among the whole population.
BTW looking forward to the Ascension miniseries coming up on Syfy.