Boy they sure are pretty machines though, even if the keyboard is meh.
Some kind of wifi modem is great with them. Saves fooling around plugging/unplugging cables to switch them between host boxen.
I've been making my own wifi-serial boondoggles with an ESP8266 module and a MAX3232. The boondoggles both listen on a port for an incoming connection (ie; using it on the host side of an old Unix server that can't run a TCP/IP stack), and provide a simple command shell for making outgoing connections. I think I am going to try to make an ESP32 version that is backwards compatible though, because the 8266 isn't beefy enough to do SSH, and I'd like to be able to just connect directly to foreign hosts rather than leapfrogging through a host on my own LAN.
The software isn't really pretty enough to publish yet, but I plan to do so once I make it a little better. In particular I want to hack up some kind of termcap code in arduino, so I can translate between terminal protocols on the fly.
Anyway, I am rambling on and on. I blame the curse of the grape! The easiest and most useful way to get up and going might be to grab a cheap raspberry pi (running Devuan GNU/Linux, of course, if I dare shill for it ;D ), a USB-serial dongle, and a null modem gender changer. Then you can just hang it all off the back of your terminal, without having to make long cables or otherwise fart around, and it's all out of the way and tidy. For extra points, run emulators for a variety of period correct systems on the Pi. PDP-8, -11, CP/M, etc. And then when you are done playing with old stuff, you still have a fancy modern Unix machine hanging off the back, that you can use for anything that has a suitable commandline program.
Serial terminals are really really awesome and fun, because it's quite easy to use them with modern Unix machines and actually do real work. There is something very compelling to me about working that way. I hope that you come to enjoy using it, and hold onto it! But if you do decide to get rid of it at some point, well..... I wouldn't mind adding a Hazeltine to my collection. I do not yet have a serial terminal installed in every room of my house yet, after all! :3