I've used the Kepner-Trego decision-analysis model personally, in business, and in volunteer groups with great results for decades. Read the details in The New Rational Manager:
http://www.kepner-tregoe.com/knowledge-center/books/the-new-rational-manager/For me, the key is breaking down the problem into bites that you and others can look at pretty rationally, then rolling the results back up to see which option suits you best. I particularly like that K-T shows you how to prepare for good news as well as disaster.
In the spreadsheet I use most often, you list your Musts and and evaluate your options to see if they satisfy them, yes or no.
Any options that get all yeses on the musts then get evaluated on a 1-to-10 scale for the Wants, which you've separately ranked 1-to-10 in importance to you. Then you use the power of excel to crank out the scores for each option. If the totals don't match your gut instincts, you can then go back and revisit the rankings of your wants and the scores you've given the options. But you don't have a big, fuzzy, religious argument about which choice is "better."
To take a popular MMM question, where should I live?, you might start with these Musts, stated to trigger yes/no answers:
* I speak the language of at least half the other residents
* it's legal for me to move there
* There are at least two Indian restaurants that I could get to without driving
* A three-bedroom home costs less than 500K.
Your Wants and their scores might include:
10) good public schools
10) near a redwood forest
9) wide variety of high-quality Indian restaurants nearby
8) lots of accordion music
5) inexpensive housing costs ( price, taxes, utilities, ...)
2) near Aunt Martha
1) moving legally takes a minimum of red tape and hassle
Given your Musts, you are probably able to eliminate wide swaths of the world based on language alone. Who cares about the price of housing in Brasil? This culling saves a lot of research and discussion time.
Next, figure out how to consistently evaluate how well an option meets each want. Maybe you can find an on-line ranking of schools to start, then verify that each of the options also teaches real science. If you can bike to the redwoods, a place gets a 10, day trip gets an 8, long plane ride gets a 1. The scores would be 100, 80, and 10 respectively.
When you look at the totals, you might say, why does moving to Seattle rank over moving to Madison? Now you can start to talk about what you'd rather be near: the redwoods or your aunt.
Once you make and act on your choice, the spreadsheet can help you focus on why you are on your current path and take advantage of the parts you value. If you move to Seattle to be near the redwoods, then go visit the redwoods, especially while you are making new friends. Heck, look for friends who like hiking in the redwoods.