The problem with the Circle Trip Explorer is that it has to include Africa which, for some of us, means it is of no use (two separate work-related trips to West Africa (Ghana and Nigeria) 20+ years ago cured me of any desire to ever go there again).

This would be a great ticket for those of us who want to go to Europe (UK) and also the US, which could be done as a side-trip as 'extra' legs in the US aren't needed but the legs could be used in Europe and Asia. However, the requirement to include Africa as one of the continents is a deal-killer, at least for me.