Both Dave Hussey and I flew to Chicago from SoCal for the RPM Chicagoland meet, and we both took several models. I suppose your experience depends on the TSA folks you meet, but my perception is that they are getting much better and friendlier. I do make a point of saying that my carry-on bag has model trains in it before it gets to the x-ray machine. I once had a TSA guy say, "Is that a 4-6-6-4?", and he was right. Last summer a TSA guy in Sacramento who didn't hear my warning said, "What's in this blue duffel?" After I said, "Model trains.", he said, "Oh, that's what those are!" This year going to Chicago the x-ray guy asked, "So where are the cars and planes?" Freight cars are really easy, because they don't have any electrical wires.
I now carry models in Plano model 23630 (now 2363001) polyethylene boxes, which hold three HO cars up to 60-ft. long. Just cradle in a layer or two of small bubble wrap and slide in up-side-down. The utility boxes protect the models completely, and you can put several boxes in a small duffel or similar bag as an airplane carry-on.
Their model 2373005 (was 3730) holds four longer HO cars or locos.
Maybe TSA Pre-check helps, but I have been carrying models this way long before that started. The bubble wrap cradle easily allows models to be slipped in and out of the clear boxes, if someone wants a closer look. But I have never had that happen in a decade of using this method.
So restrain your previous fears of carrying models on airplanes and take some with you to the next meet. TSA and the airlines are much more worried about Samsung 7 cellphones.
My congratulations too to Mike Skibbie and his crew for a great meet.
The pylons around the hotel made it mostly unnecessary to carry a schedule. And I agree with Dave that the open display / vendor room was really enjoyable.
Laguna Beach, CA