Skeet McCracken's Profile

You could hang cooked bacon to let the fat drip off. I'm reaching here.

I checked out quite a few couches like that recently, and while I think they look functional and cool, I was constantly surprised at how uncomfortable they are. One of the few that I tried that was comfortable was at Urban Outfitters, similar to this one.
http://www.urbanoutfitters.com/urban/catalog/productdetail.jsp?_dyncharset=ISO-8859-1&_dynSessConf=-2365239786719709610&itemdescription=true&itemCount=-1&id=13511381&parentid=A_FURN_FURNITURE&sortProperties=&navCount=4&_D%3AnavCount= &navAction=poppush&color=&_DARGS=%2Furban%2Fcatalog%2Fcommon%2Fitemlink.jsp

A daybed is the best bet if someone will be sleeping on it every night, but they are not the most comfortable to sit on. If you're looking for something that a guest could sleep on how about a futon or a long enough couch for someone to stretch out on? If you want something that won't take up as much space, or that won't look like it is a piece of hybrid furniture, you can get a sleeper chair. Here's one at world market, they call it a sofa but it's just a large chair.
http://www.worldmarket.com/Handcrafted-Furniture/living-furniture/upholstery-sofa/Dylan-Guest-Room/lev/4/productId/3338/Ne/1100001/Ns/NEW_ARRIVAL_FLAG|1||CATEGORY_SEQ_2889|0/N/1100039/Nty/1/view/10000/index.pro

Whatever you do, give anything you think you want to buy a test run, and don't buy it unless you can find a sample to sit down on.