I would be very surprised to hear of anyone without ICU experience could landing any ICU contract position. Hospitals EXPECT the traveler to essentially walk in the door and start taking care of patients.
As far as options, if what you want to do is ICU or ED and you don't plan on traveling for another 1.5 years anyway, I'd go into the area that you want to work in. I started traveling after 1.5 years experience in a large (900+ bed) hospital. You really learn a lot in that amount of time. There will still be some positions that won't accept you right away because they require 2,3,5 years of experience. But there are many, many that require only a year of ICU experience.
If I were you, on your course of action, and wanted to end up in ICU/ED, here's what I would do: I would try and land a job in a large, high acuity ICU. After being there for about 6 months to a year, I would talk with the ED manager and ask about getting some orientation in the ED and work a shift a week or a couple of shifts a month there if at all possible. This would make you much more marketable because you could do either or both. There are several positions I haven't qualified for because I have never done ER and they want someone that can float there. Just my 2 cents.