That is a nice collection you have there!
The beautiful thing is, these soldering irons never go out of style - you can put one in a drawer and 40 years from now pull it out and it will still work.
I have 3 or 4 of these kicking around in my garage as well. I learned to solder when I was ten using one of these.
Here is something I have found very useful to maximize the performance of a soldering gun. Before every use, repeatedly loosen and tighten the screws/nuts that hold the tip onto the gun. That cuts through the oxide layer on the metal and gives you a good, low-resistance electrical connection. If your gun doesn't heat up very quickly, try doing this.