Bob, I've been a member for over 10 years and in my opinion it is the best $25 you can spend. As geneg pointed out, the 4 issues of the Gristmill plus the special publication are worth the price of admission.
I have only been to one national and that was in Kingsport, TN. I enjoyed it, although it didn't have as large an attendance as the ones in the midwest.
Meets generally consist of "tailgating" in the parking lot that starts at a very early hour. Then inside there is a large trade room for more buying and selling and if that isn't enough there may be an auction. Plus some guys are even set up in there hotel rooms.
Displays are a big part of the meets and there will be perhaps 30 or more of them. In addition there are trips planned to interesting places in the area. These are optional. There is also a ladies auxiliary that plan events to keep the wife busy, unless she's like mine and prefers the tool end of things.
NOTE: The spring Meet is in Springfield, Illinois, NOT Indianapolis. It is June 14-17. The link below will get you to the web page you need for more information. If you intend to go and want to stay at the hotel where it is being held, you need to get your reservation in asap.
If you have any specific questions, feel free to PM me
https://www.mwtca.org/tool-meets.htmlMike