Several year reader. First time poster. Love this site and all the knowledgeable comments.
The 3 times income is a pretty standard formula used to calculate maximum mortgage. Personally, I have never owned a home that was more than 2.5 times max yearly income. Currently I am in a home that is 2 times my max yearly income. Its about your comfort level and your perceived job security for both of you.
Ideally, it would be nice to have a mortgage and monthly bills that could be covered on one income, should one of you lose your job, develop health problems, or chose to stay home with kids. Economic stress on a daily basis makes life very difficult, as most of us can attest to at one point or another in our lives, so make sure you make wise choices and live within your means. Remember that you can always move up if your economic situation improves in the future.