We already had status with United, and we are hub captives, so our choice was made for us to a decent degree. I mean, there are always options, but if you are trying to streamline and minimize stress, I would pick one and stick with it to get status. For us, we needed an international airline, so that knocked Southwest out as our go-to airline. But if you are flying somewhere in their network, I would definitely check them out since they have great leg space and free checked bags. And I am not saying if fares were significantly cheaper on any of the mainline carriers we would pay a lot more to fly United; we wouldn’t, but that never seemed to be the case for us (probably because we are located at a United hub). I do avoid ultra-low-cost carriers because I honestly just find them miserable to fly, and if you have extra gear, the deal quickly disappears in a cloud of dollar signs for all of the add-ons. Basically, each airline has pros and cons, and you should do some research if you have choices in your market for what fits your situation best.
Once you pick an airline, or you choose a couple that you are interested in, get to know their lap infant and child travel policies. I will speak for United since it is the program I know best, but they offer a lot of extra baby-related items to fly ‘for free’ and are fairly family-friendly. What I mean when I say ‘for free’ is that you are not charged extra if you need to check (or gate-check) a stroller or a car seat, and you get an extra carry-on for free for your diaper bag if you are traveling with your baby on your lap. If you buy your kid their own seat, then you don’t really need to worry about that (don’t worry! There are other things to worry about!). If you haven’t traveled with your baby yet, and your memories of flying are pre-kids or just no kids, buckle in, friends; you will have A LOT OF CRAP TO CARRY. Don’t worry; I have a starter list and recommendations here. And to give you a glimmer of hope, when you do fly by yourself or sans kids after you and your family start having wonderful and fulfilling vacations together, life is such a freaking breeze, and everything is easy. Enjoy it.
In reality, you will fly more than one airline, probably, especially if you do any international travel unless you live in the magical world of EWR, JFK, ORD, SFO, or [insert any giant international hub here] and can just fly non-stop anywhere your heart desires. But my tip is to make the vast majority of your travels easier, and picking one airline means the rules and procedures will be burned into your mind and take some of the stress of the unknown out of your planning. You’ll need that brainspace for something else, I promise.