If a book that would help residents of the greater Bay Area were published in Chinese, would it be better to print it in traditional or simplified Chinese characters?

I know there are two forms of Chinese characters, traditional and simplified, and that Mandarin speakers are more likely to read the simplified characters. My question is, Which would be the more universal? That is, which would be comprehensible to the greatest number of literate Chinese in the greater Bay Area—SF and its surrounding counties? Can those who understand the simplified form read the more traditional characters? Can those who read the traditional characters read the simplified forms?