LOL! I was going to say what short&naked said - there's no such thing as "I know the (insert instrument here) will go (insert direction)." But if we assume, dangerously, that you're right, then I - personally - would go long EUR/USD since it would probably be the benefit of any dollar crash. But if you're just going to speculate that the dollar will weaken against "some currency", then it's rather important to know what that currency is, don't you think? If all you're talking is the dollar index, then pick the Euro, as it is the majority weighted.
It will be interesting to see what will happen to the many struggling EU exporters at EUR/USD 1.36 and beyond. This is probably the last thing the EZ was hoping for with everyone QE and them still sitting back worried about "price stability". The funny thing is, Trichet and crew did the right thing, in my humble opinion, but not in the face where everyone else throws caution to the wind. The EUR should soar against...well, pretty much everything. Meaning they'll also be the last place anyone will want to shop for goods.
A few months ago after the crash, I was about to load up on dollar short positions. After all, we had to collpase with all the debt, right? Instead, the dollar soared. So much for prognosticating the market. You have NO idea what is going to happen. Maybe high inflation, maybe deflation, maybe neither. The market may soar or crash. The recession and things get a lot better. Picking directions is a loser's bet. The economists range from very gloomy to optimistic. Whoever is right will crow and the rest will keep quiet. So what???
The irony is that, unless something drastic happens, we're doomed to repeat the very same errors that have brought us here. The screwed up incentives, the pro-cyclical policies, all this is continuing and even getting stronger, because it's purportedly done to ensure short-term survival. But, wait, been there, done that... I don't like the way all this is developing... Welcome to the Banana Republic of America, where govt debt gets monetized, long-end rates eventually go to 20% and the Fed can't figure out how to properly communicate with the mkt.
I agree - it looks very much like after the party was over and the punchbowl taken away, the government is stepping in to restock the liquor cabinet with liquor borrow from local stores, but not before making sure everyone has their keys back to drive when they leave the party. Reckless.