According to some data I saw recently for the Philadelphia area, this is total budget, not labor broken out:

Average typical bath $15,000
Top 1/3 bath $30,000
Top 5% $88,000

From Cost vs. Value Report:
typical 7x5 bath midrange fixtures and finishes: $18,000
upscale 100 square foot bathroom: $55,000.

The labor is going to be less of an overall %age of your bath, than in a smaller bath because the smallest bath needs essentially all the same labor as a large bath; it just takes longer in the larger bath,so there will be an incremental increase, but your labor is Not typically going to be twice that of a bath half the size of yours.

Thanks for the response. If a contractor quoted me $20k for the labor, would that be reasonable?

The best way to find out is to get multiple quotes and compare them. There are so many variables in project scopes and geography that it's hard to provide that specific of feedback.