If you want to bring more than one pair of boots with you on a trip, plan to wear the heaviest boots that you can remove by yourself easily, and put the other pairs in your luggage.
Boots with metal attachments like taps or harness rings should go into luggage that will be checked.
Use good judgment on the boots you are planning to pack, because if the airline loses expensive boots like custom Dehner boots, you'll be quite an unhappy Bootman. If you want to have tall patrol boots with you, you may consider bringing Chippewa Hi-Shines if you have them, because they are less expensive to replace if lost.
These days, where going through the security checkpoints can be annoyingly slow, it is perfectly alright to wear boots to the airport and onto a plane.
To reduce the overall amount of weight that will be in checked baggage (and to avoid an over-weight baggage fee), wear the biggest, heaviest boots that you are planning to bring, provided you can take them off reasonably easily before going through the magnetometer at security. That takes the weight off your shoulders in carrying them in luggage, and also then those boots don't “count” as luggage so you can preserve space in checked luggage.
However, the point: “if you can take the boots off reasonably easily…” is very important. Obviously, if you need someone to help you take boots off at the airport, that will not work since you would unnecessarily delay lines at security and make people angry.
Another reason you want to be able to remove your boots is if you are on a flight lasting more than three hours. To avoid DVT (deep vein thrombosis), which can throw a clot and kill you (especially if you smoke), take your boots off at your seat so you can bend your knees, wiggle your toes, stretch your ankles, and keep blood flowing in your legs. By all means, do NOT wear boots that go above the knees while on a long flight. The boot pushing against the back of your knee will slow blood flow, and DVT could be a deadly result.
While it may be illegal to import boots made of snakeskin into California or some other countries, as far as we have heard, it is not illegal to carry boots that belong to you in luggage or wear them on your feet. Wear what you like, but if you have any concerns or doubts, choose all-leather boots to remain on the safe side.