In the last game I played (Egyptians), I played a sort of modified "Switzerland" strategy. The only war I ever declared was early on when I smashed the Romans to claim the island we were both on for myself.
Anyway, I avoided MPPs like the plague, and was very careful with RoPs. Only two times in the entire game did anyone ever declare war on me. Both times were because of tribute demands that I refused. The first time was England demanding Industrialization, and I refused. My response was to trade Industrialization with every other nation to get them to declare war on England. I then sat back and let everyone else do the fighting. About 20 turns later, there was no more England (revenge is sweet). I had already changed over to Democracy when this war started, and never had any war weariness.
The second time was Germany doing the demanding. I refused their demand and they declared war. This time, I didn't expect a declaration of war. My military was equal to theirs, and we'd had nothing but good relations in the past. Anyway, I used a similar strategy, though the proliferation of MPPs made sparking a world-wide war much easier. It became Germany and France against the rest of the world. Once again, I just sat back and watched the fun.
Interesting note: France had an MPP with Germany, but because I didn't actually do any fighting with Germany, the MPP didn't trigger against me. I kept polite relations with France throughout the conflict.
After 20 turns, the war was still raging (neither coalition making much headway vs the other). So, I cancelled the military alliances I had forged to spark the war, and then asked Germany for a peace treaty. They agreed, and relations between us instantly went back to polite. I didn't expect that. What was even better, because I properly ended the alliance pacts before making peace, I didn't take a reputation hit. Again, I was a Democracy during the war, and, again, I suffered no war weariness.
The game ended when I built the UN and called for a vote. 9 of the original 12 civs were left, and I won the vote 7-2. Interestingly, Germany was one of the 7 who voted for me.