personal preference is that flash is an "addon" or site enhancement. Im personally not a fan of sites that force the flash intro (without skip) or too much flash in the site or the whole site in flash. There are allot of people that disable it & dont bother so you lose a good % of people there too. Not everyone keeps it uptodate so then your forcing people away to download a newer version etc..
Use mainly for small elements & do the rest in gif & jpg (even allot of people using png too I believe)

best of luck either way tho!