to answer the OP's question:

test-driving:
we test-drove on the lot. we also have a neighbor who has one, and he let us play around.

how did I know? we were originally looking at suburus, but we are a "honda family" - and the only reason we were looking outside honda was because we both disliked the CRV and wanted a smallish crossover. I realized I hadn't really been paying attention to the honda line because when I went on honda's website after I had resigned myself to getting another civic when I was like "what is this 'fit?'"

the more I learned, the more I liked. we test drove one, and I liked it even more, and then my neighbor showed me what he hauls around in his and I was sold.

 

After weeding out possible cars based on things I could research (reliability, MPG, safety) I had three major "make or break" items that I looked for when I went to dealers to sit in and drive cars. They were:

1. Good cargo space with a flat or nearly flat load floor.
2. No major ergonomic flaws - in general, cars without a telescoping steering wheel didn't work out for me.
3. A low rev'ing (i.e., quiet) top gear for highway trips.

The AT Fit and Vibe/Matrix were about the only cars to meet all three, and between those the Fit is way more fun to drive.