90 days is short, which is fine for Refurb... a year seems fine for me.
In general, if you are going to run into manufacturer issues, they are evident fairly quickly. Other issues tend to be wear and tear related.
For one of the companys that offers "longer"... Longer only matters if they "honor" it. Since I am new to DSLRs in the last two years, I did a LOT of research before picking the Canon camp. It would have been easier for me to go for one of the other brands since my father owned a few of their cameras. One thing I came across was a lot of service nightmares of either:
1) The company declaring it wear and tear and charging... i.e sorry, this was misuse, we can fix it, but it will be $XXXX
2) No ticky, no service - I also heard a lot of complaints of service REFUSING to service any pieces that did not have proof of purchase though an authorized dealer. This is regardless of age, but pretty much you bought used gear, you are SOL... They would not even SERVICE IT.
As an interesting comparison.... Take a look at the complaint board here for canon:http://www.customerservicescoreboard.com/Canon
and here for Nikonhttp://www.customerservicescoreboard.com/Nikon
Canon is ranked 12th, with over all POSITIVE
Nikon is 200 something... basically in the middle.
Length of Warranty is one thing. Quality of service, price of service, etc can be something quite different.
I found dozens of complaints like this one before going down the Canon road:http://reviews.cnet.com/digital-cameras/nikon-coolpix-s8100-black/4864-6501_7-34182242-14.html
Your mileage may vary, and I am sure there are similar stories on the Canon end too... But the more I searched, the easier I found it to find more for other manufacturers than Canon, and Canon, while shorter warranty seemed to be faster and more responsive with repairs, warranties, etc.