I have a question in regard to client expectations. Is is realist to expect a top 5 ranking at both Google and Yahoo! at the same time? I have a client that ranks consistenly in the top 10 for 4-5 keywords on Google, but nowhere near the top 30 in Yahoo!.
Now I have read Yahoo! have some different ranking standards than Google (presumably they attach a lot of importance to their 300$ directory), which makes a global seo campagn a bit harder.
Although, I would like to be able to guarantee to my cleints a top ranking across all major search engines. Is it realistic?
Realistic or not will depend on what resources are put to it. I have many clients that are #1 on Yahoo, Google and MSN at the same time, so just top 5 is a lot more reasonable and realistic an expectation than that.
I would not guarantee. I hold those nice position for a lot of queries but there are others where I hold great positions at Google and MSN but not at Yahoo. As Ammon says, it is a matter of resources and I am more excited about new content creation than I am about chasing the SEO Trifecta - with the extra Yahoo traffic being possibly worth less than the opportunity loss of more content.
The 3 top SE's have differing requirements for "Top Ranking". If the competition is not too high you could top different engines at the same time. One solution is to duplicate your site contents on a new URL and optimize it for msn or yahoo. It works.