Personally, I can't imagine a situation where I would build a Flash site, period.
Things may have changed in the past year or so, but Flash only is a poor choice if "
SEO" (search engine optimization) is an issue for you - it should be!
Half the battle with any site is
making your sight "viewable" to as many folks as possible. An all-Flash site fails this critical test.
FWIW.
Best,