Not-so-recently with a couple of my projects, I've found examples of why you should block to show off.
First up, the Burridge Lake Aran Afghan. This was a massive undertaking that I wouldn't mind doing again, and probably will someday. As written, it's a 3-panel throw, perfect for your couch. I made it a queen-sized bed coverlet. Huge. I added two panels and lengthened all of the original parts. Four of the five panels are mirrored pairs. I was blocking the panels after I finished them, as blocking an entire queen-sized blanket wasn't going to happen in our apartment and it's much better to block before seaming so all of your edges are straight and all of the pieces are the correct size.
Once I had the final two panels of the original blanket done, I had one blocked and one unblocked, and there is a huge difference. People are always sure to block lace, typically block colorwork so the stitches line up better, and don't always block cables. You really, really should, and here's why:
The cables flatten out, lie nicer, and look better once blocked. The center cable panel truly is the same, the only difference being the direction of the twist so they mirror each other. There's over an inch of difference in width between the two of these, and they're only 13 inches wide to begin with. The trinity stitch also lies flatter and looks better. The edges play nicer when seaming, and that's why even a stockinette sweater knit flat in pieces should be blocked before seaming.
Secondly, I have a project from way back, the Amethyst Wrap. I only had two skeins of the yarn used for this one, so knit them all and then realized it just wasn't enough. Over the summer, I visited the States again, got more yarn, and got the project out of hibernation. This one also has a few inches of difference between the blocked and unblocked sides, and is a combination of cables and lace:
It stretches out a bit, and becomes a lot smoother and more defined. I do love seeing the difference blocking makes!
Again, blocking is important for most knitted items, and there are very few things, like amigurumis and socks knit from 100% acrylic, that I don't block before considering finished.
Coming soon, FO posts for the Blanket of Awesome