Another concern is what type of smoke detector you have
I never gave this much thought before, but this week a local TV news program had a two part series
about the differences between ionic vs photoelectric based smoke detectors.
They did some testing with the fire department and found that the photo cell type were much faster
in detecting smokey smoldering type fires which are often the most deadly
The ion based ones are the most common out there and make up the majority of the market
and they tend to give better results with flaming fires, but the photo type gave the same results
as the ion based under these conditions.
I usually don't pay much attention to these "investigative reports" but this one is really interesting
and a little frightening - also may explain a lot of those "I never heard the smoke alarm go off" stories.
In the end it seemed the best bet are the dual mode versions that have photo and ion technology
I have about 5 in the house I am going to replace soon (anyone see any deals on dual mode detectors?)
http://www.wthr.com/global/Story.asp?s=6552929