I question the competence of the AI at times.

[Suicide Junkie]

Star destroyers 20 turns in? Zwuh?

No surrender is a good thing. Otherwise the game ends quickly with a domino effect.


If you want a strong AI challenge try:
CBmod v1.5
1) Install the imagemod if you don't have it already
2) Let the AIs be chosen randomly. This way they will be generated properly.
3) Choose Medium tech start. If you want more of a challenge, use Low tech start and Med/High tech costs.
4) Choose high difficulty and NO BONUS. Team mode for extreme challenge. Low bonus instead of none if you want to be steamrolled.

5) And, of course, don't ask for surrender or offer cheap trick trades. Turn the option off in game setup if you feel the need, or just don't do it.


PS:
Most of these tips, aside from the "use no bonus" will help in stock as well. In Stock, it is fairly easy to beat even AIs that are on high bonus (5x build rate & resources).