Just got back from a trip to Rome and cruise from there across Italy, Spain, etc. and here is what I found in both research before going and in experience. If you have regular ecigs as opposed to a VV mod such as Provari or GGTS you will have more issues. I know that seems backwards but the more NOT like a cigarette it looks the less people mess with you. If you have your liquid marked with a professional label rather than a sharpie then that sometimes helps. However you carry your liquid you need to keep it in a Ziploc bag with all your other liquids like shampoo etc. I also suggest keeping all your ecig stuff in one single case, pouch, or Ziploc because they WILL want to look at it no matter where you put it so you might as well have it where they can tell you aren't trying to hide anything. If you are going over seas like I did (which I doubt since you are flying SW) then make absolutely certain that no matter who asks you whether it be the security at the airport or the guy next to you at the restaurant, you say that it's a medical device (again much easier if it doesn't look anything like a cigarette) or at least that your doctor told you to use it because your smoking caused medical problems (which is true) and this would help you. I told everyone that it was a "vaporizer" or "personal vaporizer" which is obviously true but in the airports all they needed to hear are the words "medical device" and they zipped up the case and said I was good to go. I carried on my Provari, Raptor tank with replaceable atty, vivi nova also with replaceable atty, bottle of menthol liquid and vanilla cream liquid, and 4 18650 batteries in a large nylon zipper bag. Then I kept my GGTS with Ody 2 +Kir clear tank extension in my pocket which I would remove with the rest of my pocket stuff so they could see it was "something I needed to carry with me". Most people didn't think anything of it in public but on the ship, in the airport, in restaurants, stores, etc I had to explain frequently that it was a vaporizer I used for health reasons. My research also said the same things. In a lot of airport in US and abroad they frown on ecigs and with take them from you if you display them as such (hold them and use like a cig, use a PCC that looks like cig case etc).
So in a nutshell for you and others reading this, if you are going to stay in US and have devices that resemble cigarettes then just stay low key in the airports and on the plane and don't try to stand out with them. If you are going overseas I strongly suggest buying a mod that can't possibly be mistaken for a cigarette or other smoking device and make absolutely certain you call it a medical device and/or a vaporizer.