So I thought I'd write a quick little update on which office app I use. As I mentioned earlier, I have both Docs to Go Full and Quickoffice Pro installed on my Android (both were free at one point on the Amazon app store app of the day). I haven't used either of them a ton, but from my usage, I've found the Docs to Go spreadsheet app to be MUCH smoother than the Quickoffice spreadsheet app. I can scroll up and down a sheet with no problems on Docs to Go; scrolling up or down a sheet (especially one with tons of formulas and formatting) will be very laggy / jumpy on Quickoffice.
The one minor downside to Docs to Go is that the formatting is not always consistent. In my models, I like to "fill" all the cells with a white background (to get rid of the gridlines), but they are still visible in Docs to Go. On Quickoffice, the cells backgrounds are formatted correctly, although I did find 1 or 2 errors in formulas that were not apparent in Docs to Go.
EDIT - just realized i could not edit my spreadsheet in docs to go because a "feature was unsupported". Apparently, docs to go does not play nice with the Median formula. lame. This is obviously unacceptable, so now i've got a very pricey excel sheet viewer.
On the other hand, I finally got around to trying Office Suite. It's awesome! No formatting issues or editing issues. I'll be using this instead of the other 2 going forward