There have been lots of good suggestions on here so far. Since you're in the market for a new rod, I'd make a trip to LRO where you are welcome to test a wide variety of rods. Don't be shy...test as many as you can.

With a budget of $700, you should definitely test some of the more expensive rods, like a Winston LT5 (one of my personal favorites) or a BIIt. These are beautiful rods, and they come with nice tubes. But, like PeteCZ recommended, there are plenty of great casting rods that don't cost a fortune. I also think the TFO Pros are great rods. Plus, they have excellent warranties.

If you want to get a single rod, I would recommend going for a 9' 5wt. This seems to be a good, all-around trout (possibly light bass) rod. My first rod was a 9' 6wt, which is great for big tailwaters, but sometimes feels cumbersome on smaller streams. My second rod was a 8'6" 4wt, which I love. However, it is more difficult to cast streamers and other heavy flies with this rod. For this reason, I think you'll find the 9' 5wt to be a good compromise. In all honesty, you'll probably end up buying several rods before you know it...that's just how it seems to go...

I also agree with Jeffnles. Don't buy a rod just because it can throw a tight loop at 60 ft. I made that mistake, and that rod has been sitting in my closet for over a year.

Hope this helps,