I bought an Ikea Ektorp corner sofa. I've only have it about a year, so I can't tell you about the longevity of it. I imagine it isn't the sturdiest thing... however, as I told DH I'm about to have 3 kids under 3.5 so I'm fairly certain they could completely trash the most expensive, well made sofa in the history of the universe in about the same time it will take them to trash this one!
But so far, we've been very happy with it. I find it very comfortable, though it doesn't really come with throw pillows so I bought a few extras.
The best, best, BEST thing in the universe about this sofa is the seat cushions. Most sofas have the cushion and a cover, and if say, a hypothetical potty training 3yo DD pees on it you can wash the cover and all you can really do is stick the cushion out in the sun and hope to bleach it a bit. The Ektorp seat cushion is a piece of foam (maybe 4"?) covered with a down-filled slipcover, and THEN the cover. So you can take both the down-filled slipcover and the cover off and put them in the washing machine. I can't promise that's actually in the washing directions, but I will say that we've stuck the down covers in the washer and dryer (low heat) a few times now as a result of these accidents, and haven't had a problem. And the down slipcover is thick enough that no wetness made it through to the foam.
Also check out the as-is department. That's where we got ours, and I swear they always seem to have at least one at our Ikea. It was 50% off, so an even better deal.