Well the reason we aren't seeing much stealth or assination is because of the level of the ninjas that are involved. Its not like they are infiltrating some obscure area or assassination a weak lord. These are Jounin+ leveled ninjas and sneaking up and ending a fight before it starts isn't going to happen. Instead the stratigic aspect becomes more prevelant, at least in Shikamaru's case. Sasuke combines a great stratigic mind with a diverse set of jutsu and a natural enhancement. Naruto uses endgame type techniques and has the predictive ability to set up opportunuities to use these skills. And despite all the different styles and techniques, we see them used to great effect and thats whats makes it fun.

As to the theme of Naruto, I would have dto disagree with you that hard work pays is the theme. That became a main theme more with Rock Lee, where as Naruto wanted to work hard to become Hokage was his way of seeking out acceptance. But in Naruto's case it wasn't the hard work that seperates him. Its his natural abilities combined with hard work that makes him special. And at this point in the manga, all the top ninjas have worked hard to get where they're at, so hard work trumping natural talent isn't gonna be seen as much as it was at the Genin level.

The primary theme of Naruto, which is still a priority, is the loyalty and allience to your allies and teammates and friends. Whether it was Kakashi's training on teamwork, or Shikamaru's speech before setting out for Sasuke, or to this whole Arc where Naruto searches for Sasuke via Itachi, its always been about never leaving that teammate behind. And this theme is what motivated Naruto to train so hard.

PS. I just thought of this while typing but I can see a final combo attack with Naruto's Rasen Shuriken and Sasuke's still unrevealed "that" jutsu, which I and most believe is a Katon jutsu. Naruto said that his wind manipulation could strengthen Sasuke's fire, a kind of premonition that I think will come to pass in a final confrontation with ....?