Re: Image map and SEO query
It's particularly poor accessibility if you omit the ALT attribute (and thereby use invalid markup, to add formal incorrectness to real injury), as above and as so often.
It's better that you don't know that. Think about accessibility, usability,and simplicity in navigation, and search engine friendlyness comes more or less automatically.
"SEO" is a buzzword used largely to sell questionable services and misguided principles. It promises "optimization", even though it should be obvious that no optimum can ever be reached in the world of varying search engines (which are largely intentionally varied to fight against evil forms of "SEO").
I wouldn't be surprised if it turned out that Google traverses the href attributes in <area> elements on saturdays only. But I would be surprised if information about internals of Google were revealed in a manner that justifies an assumption that the information is correct and stable.