This is good advice. Everyone is different. This may help. There is a lot of good information on the different breeds.Well, everyone is going to tell you something different because everyone has different goals and priorities when getting chickens... You have to ask what your primary purpose is in having the chickens so you can prioritize those qualities above others... I don't think you need to worry about the heat as much at 4000 feet, maybe you will have snow in winter, so will need a better chicken house up there. Definitely will have predators, so will need that good chicken house and lock up at night. Are you more interested in egg production, personality as pets, should they be colorful/pretty/unusual? Are you more interested in classic or Heritage breeds? Do you want large birds or bantams? How involved will your children be? You can help us advise you if you can be more specific about your expectations for the 4 you can have... Glad I can have more than 4 and roosters, too. Some birds, like Cochins lay more in the winter months, so if egg laying is more important year round, add one of those. Maybe you will want one of each from each category?
http://www.feathersite.com/Poultry/BRKPoultryPage.html#Chickens