Recently flew Southwest from Seattle to DC with layovers in Denver on the way and Chicago on the way back. I packed 2 Ego batteries and about 20 10ml bottles of juice, chargers cartridges etc. in my checked bag in a plastic divider container and put one of the e-cigarette-forum.com business cards in the plastic container. In my carry on I had a nicostick style mod along with 4 510 batteries, 4 attys and 10 6ml bottles of juice. I put the bottles of juice in a plastic bag and ran it through the Xray machine just like it was shampoo and toothpaste. No one said a word about any of it. Vaped with my Nicostick openly in the Seattle, DC, Chicago and Denver airports but didn't exhale large amounts of vapor anywhere inside. Vaped. again with the Nicostick somewhat openly on all the planes, never blatantly exhaled vapor, but wasn't blowing it down my shirt either. On each plane the other passengers in the seats next to me asked what it was, one even asked if it was a asthma inhaler. I explained what it was and one passenger smoked and I gave her one of the forums business cards. Never had a problem anywhere.
I first started using the E-cig a couple of years ago just for air travel. I've vaped on planes and in airports a lot over those two years, but up until recently it was with the E-Health E-cig which you can't get much vapor out of no matter how hard you try, so it was barely noticeable anyway. This was my second trip since discovering good PV's that will actually create a decent vapor, and no problems on either trip. Since discovering the good PV's I've given up analogs all together!
On my first trip with a 510 I was in the Las Vegas airport blowing out way too much vapor when an airline employee (not an airport employee) came over and told me there was no smoking in the airport. When I explained it was electronic and not a cigarette he asked if it helped, and I told him it really helped a lot, so he said he would go tell the woman who complained that it wasn't a cigarette!
In the Denver airport there is still a smoking lounge. Since I'm no longer a smoker I could smell the stinky lounge from 100 yards or more away. No wonder non-smokers don't like those! I did go into the lounge to have a beer and vape my nicostick. Lots of smokers asked me about it and I point them all here.