Every stroke "requires" a breath so it is a good one to just get used to having a nice rhythm and working on exhaling. ?You can just take a nice long deliberate stroke to work on going longer while still being in an easy and comfortable position to pop your head up if need be. It is also a good one to be used to for siting in open water, which I believe you also mentioned.
When doing freestyle since it sounds like exertion was an issue as much as getting air, remember that long efficient strokes are better then tons of short fast ones. Bad habits are hard to break in swimming since you can't see what you are doing if you are taking tons and tons of strokes per lap try and slow down your stroke and go longer. You may go slower at first but you'll get better form and use less energy as well as keep your heart rate in check.