Okay remember you asked. ;-)
I created a cruise template in MS Excel with three worksheets. The first worksheet is misc tab to cost out: hotel, airfare, pet care, parking, shuttle, etc. The second worksheet is cruise expenses tab to cost out: cost per person for the cruise, tips, taxes and port fee, cruise discount (we have a rewards card), the third worksheet is a summary tab it compiles information from the other tabs then show the total costs; cost per night; length of the cruise; name of the ship; and destination. At one point last year I had 12 cruises in the worksheet. I have since modified it to 3 cruises.
So we determine which cruises make it into the template my hubby and I decide where we want to go. I then check for the best month that is less expensive; while still having good weather. I check the average temps/rainfall of the ports in yahoo weather. I ran those thru the template and determine the best cruise for weather, price, and ports. If the cruise is to Alaska I also check the migration pattern of the whales and if the salmon are running.
After I have the cruise I review the different types of fares and pick the one that best suits us. In the case of my last cruise (Carnival Splendor) I booked Early Saver and picked my cabin/deck on the ship. We booked over a year in advance and I watched for price drops. As the price drops occurred I put in Early Saver requests. 4 Early Saver requests in all. We had a nice bit of OBC on that cruise.
I'm not brand loyal if RCL had the best deal on a nice ship I would have picked them. It didn't happen this time. We drove to port so no airfare was needed. The template does show the cost of gasoline to drive to the port. Based on miles per gallon my car gets, miles to the port, and price per gallon of gas (I did an excel formula).
On another thread it was suggested I was not getting the best deal because I was not using a Travel Agent. I don't believe a Travel Agent would have watched the cruise price as closely as I did. I also like the control I have with handling everything myself. To me this part is fun and interesting. I costed out some cruises for my Crazysis just for the fun of it.