To be completely honest, it depends on the chicken...
Right now I have one spoiled brat of a leghorn...
Her buddy died in Aug of 06 and I felt that she needed a friend. They didn't hit if off well. Obelisk pecked her and chased her and yanked out her feathers...after about 6 months they started to get along, a little...then Penny went broody and it started all over again...
Penny was killed by a hawk a month ago. So she's by herself...and she seems fine. I sit out back with her when I can and she clucks to show me she's got something yummy...but most of the time she's roaming the back yard by herself.
We did go out to the Petshop the other day for a change of pace...which I think she enjoyed.