Try running a fort with limited no military. Rely entirely on traps, and if things get too hot, just wall yourself in, because there still isn't anything that can destroy walls.
Bonus points: Build an entirely self-sufficient fortress that's fully automated, use dfhack to disable pausing, and leave it to its own devices overnight.
Not for nothing but given how overpowered traps are right now that would be a lot easier than running one with military (whether it is 'more creative' I guess depends on how you lay out your traps.. If its just a mass of traps over a single-tile wide bridge.. Not so much).
As for the OP.. If you want challenge/creative I'd go the other way and say use military only, no walling in, no traps. If you want more artistic creative I'd design some kind of trap (as opposed to a glut of preset traps), something that doesn't involve magma (seriously that's been done to death). Maybe pressurized water that blasts the enemy out of your base, or knocks them into a hole filled with spikes, or fill the water with gators, or what have you.
The skies the limit really, but if you want something truly interesting you need to cross off magma chamber and drowning chamber (not that they aren't good educational opportunities, just that they have been done countless times and honestly aren't that complex).