I also use Google Docs, but I like Docs to Go (I use the paid version). For whatever reason, I question the full spreadsheet support in Google Docs (depending on how complex one's spreadsheets are).
Is it just me or can you not upload documents to the Google Docs mobile site? When I click for the full site, on my Droid, it tells me my browser is incompatible. So basically, how do you get a document (let's say a spreadsheet you've edited with Documents to Go) onto Google Docs from your Droid?