I just got done wiring a 7.1 system in my living room, and every last wire is totally concealed except for the few inches immediately behind each speaker. I used a combination of techniques.
The receiver sits against Wall 1; then I have speakers wrapping around in a clockwise manner. The left side of the room is open (no wall) so all the wires for the back and left speakers had to run around the right side. Whenever possible, I buried wire underneath the base moulding. If you have base moulding that isn't flat smashed down against the carpeting, you can fish the wire between the carpet and the moulding and it settles into like an invisible channel. I'd use a blunt object, like a capped pen, to gently push the wire into place.
My right and two back channel speakers sit on shelves about 4 feet high, so for that I ran the wire through the wall and got some nice "outlet covers" that are specifically for speaker wire to finish off the look. To run wires through the wall, I drilled a hole at the top and a hole at the bottom (both holes between the same studs); then dropped a piece of string through the top hole. I fished it out the bottom, tied my speaker wires to it, then pulled the wire back up through the top hole.
My left rear sits on the kitchen island (only place for it, really) so the wire for it runs along the wall for a while; then it needs to run 15 feet across carpeting to get to the island. Lucky for me, 12 of those feet is covered by my couch so I routed the wire over-carpet such that it was underneath the couch the whole time. When I got to the 3-foot stretch of uncovered carpet, I cut a slit about in inch long. The slit is covered by the couch. I took a long metal rod, taped the speaker wire to it, and "pushed" the wire through the carpet slit and over to the side of the island cabinet. Once there, I gently pulled back the carpet, found my wires, pulled them through, removed the steel rod, and put the couch back. And there ya have it...wires run underneath carpet! The wire then runs through the inside of my cabinet and on up to the speaker.
It's all about creativity, really. Make use of the furniture, layout, etc.. to hide the wires as best you can.