Everything in one site a good idea??

I have a question I was hoping some of the more experienced marketers could answer for me. I am somewhat new to affiliate and internet marketing, so please give constructive answers.

Would it be a good idea to combine everything I am working on in one niche under one massive website? F.ex. instead of trying to sell a marketing solution via a sales page, why not have a full website, like a community (using a CMS), where people can choose the area of marketing they are interested in, and then have a sales page promoting the affiliate or own product under that category?

Or is it better to have different domains, although it's in the same niche, and try to sell the products via a landing page?

Maybe have both, and gather emails from both the sales pages and the big one, to be my own JV-partner?

Comments?

Thanks!

if you will use whitehat only there is no problem
but if you will use blackhat seo then sure you must spread your work