We have been to the Universal parks the last two years the first week of March and the crowds were pretty low. In fact, if you get there when the parks open you have them to yourselves for at least an hour. Of course, some rides are going to form lines very quickly (Hulk, Mumy etc.), but we found that we can wing it much more at the Universal parks than at, say the MK, where we need a precise plan to avoid crowds.
Last year we did buy the express pass booklets, but I'm not sure we really needed them since the only really popular thrill ride we did was the Mummy. (we don't ride coasters).
We have two young boys and our park touring is focused on them, so other people who tour the parks differently may have differing opinions.