I disagree about directory submissions. They can be great, but don't submit to just any directory. A great resource for good directories, many free, is info.vilesilencer.com. If you are just planning to spam a bunch of sites to directories, be prepared to only see your links accepted on the lowest quality directories. If you are writing a thoughtful title and description for a high quality resource on the web, you'll have the better directories accept your resource. Some directories charge for the review process, and people like Matt Cutts have said this is perfectly fine so long as there is a high level of editorial policy.

If the user experience awesome, and people are staying on your site and looking around, great. If you think the 100,000 pages will make search engines love you, machines can never provide the love users can give you.