Openarena is great. It runs like stock Quake 3, but has a few extra option like automatically switch to a new map when the frag limit is hit. It doesn't have the original bots, but they can be added if you know how pk3s work and you have the original files.

There's some configuration that has to be done, like creating a file with the map names in it, or making sure the stock mods are at the bottom of the each map sets directory, etc, but I have scripts that auto-generate configurations and symlink stock files, so I can move stuff around without thinking too much if I need to.