Whilst I hate flash sites with a passion, you do get results very very quickly, and since flash is (at it's most basic) simply a drawing / animation package the results can look quite good.
Flash Sites do look a little tacky, but they're fast to make. Easiest would be HTML. ASPX would be so much better though, from a personal perspective of mine.
It would give you a good stepping - but if you want it faster you'd probably get the basics in with the extension - it would be a little harder though.