Flat vs. Silo Site Architecture, What's Better

[C-Style]

I'm in the midst of converting a fairly large website (500+ pages) into WordPress as a content management system. I know that there are two schools of thought regarding site architecture:

1. Those who believe that everything should be categorized, I.E.- website.com/shoes/reebok/running

2. People who believe that the less clicks it takes from the homepage the better.

As it stands, our current site has a completely flat architecture, with landing pages being added randomly to the root, I.E.- website.com/affordable-shoes-in-louisville-ky

I'm beginning to think that there is a gray area with this. I spoke to someone who says that you should never have a page more than 2 categories/subfolders deep. But if we plan on adding a lot of content doesn't it make sense to set the site up into many categories so we can set a good foundation for adding massive amounts of content.

Also, will 301 redirecting to the new structure cause us to lose rankings for certain terms?

Any help here is appreciated.

[NaHoku]

We've had very good results by silo'ing our content.  We do use drop down menus.  We are ranking very high (top three) for some targeted key phrases that are over two categories deep.  I'm a big fan of the silo approach.

[mjtaylor]

I am inclined to lead toward some type of siloing with a high content site. There is the very purest silo architecture which I feel Bruce Clay presents very clearly in his site articles. You can certainly vary it to be less rigid and still be an effective SEO tool.

I generally agree that MOST content should not be too many clicks from the home page, but drop down menus can go a long way to keep a lot of content close without it being unwieldy. Perhaps it will help to look at it this way: the way your structure your navigation tells Google what you believe your most important pages are - if you tell them ALL your pages are equally important, you dilute the ability of your top pages to rank better than your lesser pages.

If that makes sense to you, I hope it helps.

301 redirects are the very best way to redirect and retain the most link power. Within the site, you have nothing to worry about if your new structure has better SEO. 301 redirects do not always pass 100% of external bank link juice, but it's still the best tool we have to keep what we have already achieved.