What SPF factor would you use?

Sun's Eve Maler followed up on a Tim Bray (also of Sun) post on 'research' that indicated that sun exposure wasn't necessarily bad:

I have long been suspicious of answers to the question of how much sun exposure is good/bad for you.

I expect this is neither the official Sun line:

1. on being an employee, or
   
2. on the MSFT/Sun relationship
   

Personally, I value my sun exposure and so will not take any dramatic measures to protect myself in future standards meetings.