We chose to do the moonlight tour on our first night in DC and it was amazing! Not only was the guide knowledgeable about the monuments, she grew up in DC, so knew everything about the city. The monuments at night are completely lit up and give them an even more dramatic atmosphere than their stories already give. It was freezing cold the night we went, but the rain cover was put on and there were nice, heavy blankets to snuggle up with. The bonus for us were the big, fluffy snowflakes that poured down as we were on top of the Lincoln Memorial. What a memory! In other words, don't let the weather decide what is written in your travel journal. Enjoy!