Both Wool of the Andes Bulky and Swish Bulky looks like it would work in replacing the Rowan yarn you mentioned. The one thing that would make you go with one over the other is that Swish is a superwash yarn while Wool of the Andes would be hand wash only. The other option you would have is to double City Tweed DK or HW - depending on your gauge, one of those might work. The only thing is that you would need twice the amount of yarn.
For simplicity's sake, I would say go with the bulky Wool of the Andes or Swish :) Hope that helps!
Yeah, it's just that my husband has a lot of tweedy sweaters already and wanted something different.
Thanks for the feedback. JILL