I have LR and SSP and I'm very happy with it. If you want total control you'll need SSP for Flash but that's a whole different ballgame. SSP for LR is well worth the $25 for nice simple, smooth web slideshows that are quick to build. If you want to do a whole website you might need Slideshow Presenter - I don't have this so can't comment.
Here's a typical result:Slideshow