We have a two bedroom condo and one of the bedrooms is a huge master suite. As a bedroom, it always felt like wasted space to me. When my husband started quilting last year we decided to switch rooms because there just wasn't room enough for both of us in the sewing room at the same time.
We love it and don't regret it at all; I just wish we'd done it sooner!
I say...go for it and don't feel guilty!