After evaluating a few of them, I decided on CI since it was the smallest and lowest learning curve I felt. It didn't have all the features (it had enough for me) but I had a much better feel for what was going on, and honestly, I'm still not a huge fan of a bunch of magic in my coding (I get that in Grails). The "old" developer side of me likes a little less dynamic stuff.
Zend seems more like Grails, where it's a larger heavier framework (although Grails is lighter than other Java stuff) and for the stuff I'm looking to do, that just isn't necessary. If I'm going to do something big, I'll do it in Grails since it will run on a dedicated host. CI projects on the other hand I see running on shared hosting.