Root EVO 4G stock ROM?
What are my options for recovery images? Is there anything besides ClockworkMod or Amon Ra?


A third popular option is TeamWin Recovery Project, usually referred to as TWRP.


  If I go with either one, how do I get it installed?


Since your bootloader is unlocked, you can use fastboot to install a recovery if you download it in .img format. You do this by downloading the recovery image to your computer, plugging in your phone, and executing:

fastboot flash recovery /path/to/recovery.img


from a PC command prompt while your device is booted into fastboot mode.

Alternatively, ClockworkMod and TWRP can both be installed from apps on rooted devices. For ClockworkMod you can use ROM Manager and select the "Flash ClockworkMod Recovery" menu option. TWRP can be installed using GooManager by selecting the "Install OpenRecoveryScript" option in the app's settings menu.

A third option is to get a copy of the recovery you want in a bootloader-flashable zip file. For the EVO it will be a file named PC36IMG.zip. You put it on the root of your phone's SD card and then reboot into your bootloader and it should flash it for you. I know that Amon Ra has been distributed in this format, but I'm not sure about the others.