I would love to have a bigger chat window, but I want it to go away when in combat so I can see what I'm doing.

One way to do this might be to have an option per chat frame: Hide in combat. Then you could have a small window which is always visible, and a large window which pops up when out of combat (OOC).

Another option would be to have the window resize when in combat. Yet another option would be to have a frame be only visible OOC and another frame only visible IN combat, and you'd could set up all kinds of differences between the 2 modes, such as size.

I use WIM to get a big whisper chat window, and it disappears nicely when in combat. But I don't want to move all my group and guild chat into WIM because WIM bypasses a lo of the nice features from Chatter.

Thanks for Chatter, it's awesome!