What are the pros and cons of a K-1 fiancee visa versus a spousal visa?

Fool for the City: What are the pros and cons of a K-1 fiancee visa versus a spousal visa?
I know an American citizen who is getting married to a Canadian woman. While helping him do some research to make it a legal process, I noticed that there is a K-1 fiancee visa for her, or a spousal visa. Other than cost, what is the difference between the two?

Answers and Views:

Answer by spot
Why bother? Visa not needed for a Canadian to visit the US. Who is checking papers anyway?

Answer by Tom
If you marry in Canada, you would petition for an immigrant visa. If you
intend to marry in the US, the fiance visa permits her to enter the US
for that purpose. After marriage she could then adjust status to permanent residence. Either procedure will take several months
for processing. This site has useful information:

Answer by David
one you marry in Canada and the other you marry in the US
Follow the flowcharts here

Answer by J
With the immigrant visa route, there is the hardship of being apart after getting married. Who would want that? I personally think the K1 process is easier as well.