Sometimes links to documents go to a view, and sometimes initiate a download - how to control?

[B Price]

I'm creating a wiki with many sample documents, which users can adapt and use for their purposes. Sometimes the linked documents seem to go to a "view" mode when the user clicks on them (and the view, especially for spreadsheets, is terrible) and sometimes the links go directly to a download. How do you control this? Especially when the view is bad (like for the spreadsheets) I don't want users to think "This is a useless document!" and not bother to download. Thanks.