Question: My fiance and I are seriously considering going in for couple‘s match. We have interviewed at 10 places each, out of which 6 are common to us. Is it a reasonable decision to go ahead and apply as a couple?
Answer: Here is what NRMP says about couples match:
"The NRMP allows couples to form pairs of choices on their primary rank order lists, which then are considered in rank order in the Match. The couple will match to the most preferred pair of programs on the rank order lists where each partner has been offered a position." 
There will be no direct suggestion as everybody has different set of priorities.
From the statistical standpoint you are cutting off your chances significantly. Let‘s look at some math:
You and your fiance must rank the 6 places you interviewed at as matching pairs. In order to match, you both have to match to any of the places from the 6 programs. If either of you matches to a higher ranked program and a spouse matches to ANY program, most likely this will still be a match because the one that matched higher will sure match with the lower ranked program.
So, each of you starts with a probability of matching P1 and P2. Each of the probabilities gets decreased to 6/10 because you only have 6 programs to rank as a couple: P1*0.6 and P2*0.6.
Now, a probability of both of you matching to any of the 6 programs is: P1*0.6 * P2*0.6 = P1 * P2 * 0.36 Assuming your individual odds of matching are somewhat close, you just cut your odds by almost 3 times– by 2.8 times to be exact.
The crossed out interpretation was based on earlier couples match details provided by the NRMP. Thanks to Dr. Julio Peguero who provided feedback on incorrect interpretation and helped fixing the error. Recent updates to the NRMP provided here http://www.nrmp.org/fellow/couples.html is clear - there are no negative implications for either member as long as they rank the programs appropriately. Appropriate ranking should include all possible combinations for both applicants.
Example: Let's say Jack and Jill had 3 interviews each at the following programs:
The couple should arrange the ranking in a way that all program combinations are listed:
Then arrange the combinations in the order of preference. Obviously, all pairs with one of the partners listed as a NoMatch should go last. Make sure you include all the combinations, this is really important!