Can you explain more what you're trying to do? For example, flying SE Asia-Paris-SEA-Lima-SEA is not possible with an RTW, because of the "no backtracking" rule.
An RTW is "worth it" only if it serves your objectives and costs less than alternatives. If you're planning on flying SEA-Paris-Lima-SEA, an RTW is quite possibly the cheapest option, and thus may make sense even if you can only spare a week. (Whether that amount of travel in such a short time is fun anymore is another question.)