1. April
Well, it has the "perfect date"
which (not) coincidently happens to be my birthday.
Weather's near-ideal ("not too hot, not too cold, all you need is a light jacket"), the kids are still in school so it's a good opportunity to do some traveling. The heart of spring as things continue to blossom and plants grow.
2. May
Proximity to April, nice weather
3. March
The start of spring. The lovely blossoms.
4. November
The long hot summer is a distant memory and the start of the holiday season
5. October
The long hot summer winds down. Still have to deal with leaves though.
6. December
The winter months will be polarizing, but where I live, I don't deal with snow and the like, so while the weather may get wetter, the temperatures aren't too extreme, and nothing a nice hot chocolate or apple cider can't aid as Christmas approaches.
7t. June - September
The hotter, drier period.
7t. January - February
The colder, wetter period