Oh, see now this is a topic that interests me greatly. I personally don't think Arsenal ever recovered from giving up on a two up front formation. Suits their football so much more.
It is what worked best for Wenger, I am guessing it is what he used at Monaco and in Japan. It is a system he used perfectly at Arsenal. Especially when he had pacey forwards such as Wright, Anelka, and Henry to work with. And of course the brilliance of Bergkamp behind them.
The team had stagnated for a couple of years, but instead of just finding quality replacements for the likes of Silva, Henry, and Bergkamp leaving, Wenger decided to go with youth and change his whole footballing philosophy. One up front and a change to possession football. It is something he clearly is not comfortable with because we have never looked right. We have played some beautiful football during these years, but nothing of any real substance. We can score and beat poor defences, but any top team with an organised defence has always caused us problems and shuts us out.
The problem with our one up top is that there just not enough players in the box. Wenger likes a forward who can drop deep and link up play, but that means the wing players have to get into the box, but they hug the sides too much.
I think Giroud and Sanchez would work well up front together. Giroud has great link up play and Sanchez is a very intelligent runner. Having two in the box would force the defence to play narrower and create more space on the wings for our wingers/fullbacks