Of course it depends on what you want to do and the resources that you want to devote.

Madinat Jumeirah is my favorite hotel (group), but $700 is steep for sure. I would recommend that over Atlantis, unless you plan to spend most of your time at the hotel and/or are really into the water park (although I think that you can get into Wild Wadi, which is nearly as good as Atlantis's park, with your Madinat stay), because of the location. It's somewhat inconvenient to get back and forth to Atlantis. And Madinat Jumeirah (even Mina'a Salam, the "lowest" of the three properties, is a step up from than Atlantis in my opinion) -- the service is better, rooms considerably nicer, and amenities overall of higher quality.

The Radisson Blu (I assume that you are referring to the Deira location) is a very different location in the old part of town, with good F&B and centrally located -- you can step out of the hotel to the old souq and dhow waterfront -- but is a bit dated and not as nice for the pool. The InterCon or Crowne Plaza Festival City are nice hotels (rooms at the IC are very attractive and service pretty good), but the location, while central, is not as good (the Festival Center is uninspiring).

I like Emirates Towers a lot. If you can also visit Wild Wadi included with your stay, then this is worth considering for the cost savings -- it's also centrally located and within walking distance of some of the best restaurants in Dubai, as well as on a metro stop and close to Deira.