This is just a personal opinion, because I'm curious who does and doesn't agree:
I think that these tourneys have an ideal time frame. One day is too short (as we learned in the early events), but I really think that seven days is too long. This one just kept going and going, and as a result, the finish was a little anti-climactic, not nearly as exciting as it usually is. And most of us by then were simply tired, of both playing and watching.
I said in the shoutbox that as it went on, it felt like a kegger that had started at 8 PM, but rather than ending at 3 or 4 in the morning, stretched into noon the next day. We love the kegger, and we can't wait for the next one, but at some point you just wanna go home and go to bed!
Tournament-style DK seems to work best in a tighter window, both for spectating and competing.
One of the fascinating and exciting things about DK - and what makes it such a great tournament game - is that anything can happen in the short term. First there's what the game is dishing out, but there's also all the physiological/psychological/emotional stuff going on within the player... and the way the first interacts with the second).
Everybody having to get in all of their attempts in a compressed span of time is what really brings out the tension and drama, I think. In a weekend, you have to work harder and fight against fatigue and frustration, and an RNG that might be very ornery. Over a full week though? There's a lot of time - maybe too much time - to take it easy and regroup. And it offers the randomness too much space to normalize. If you do that, the best players are just going to win every single time (which is already kind of a problem as it is). A shorter format allows for surprises and crafty maneuvering from the less-elite players, while the big guys try to put together their risky, more exhausting, more luck-dependent big games.
There's also something to be said about having it over on Sunday. Nice to wake up on Monday and have the tourney done and past, and to be able to start the week fresh without it still hovering.
IMO: from my experience and observation, I think that three days seems just about ideal. Something like Thursday 6PM though Sunday 9PM would be wonderful.
However, with a totally different format (ie, something other than a simple "high score wins" contest), a longer time frame might indeed work. So I'm interested in hearing and helping come up with possible ideas.