Just a quick note...
Henry, Clare, and I attended Mass by ourselves again this Sunday--with wonderful results! Henry was energetic, but manageable. We stayed in the crying room--there was only one other (helpful and understanding) family-- which made containing Henry much easier.
I brought along my Moby wrap, and wore Clare when we entered the Communion procession--which worked out wonderfully. I had two hands free, which is very important when travelling with an escape artist!