Hi Todd,
Up here in Fargo, ND, our painting season starts in late April, and ending by Halloween. Reason? You need temps above 50deg. (reliably), so paint can level and dry correctly.
Where YOU live, you could paint (almost) anytime! If you decide on a total repaint, make it easy on yourself. Pick a time of year when temps aren't too hot. Painting in the 70's is ideal. Comfortable for you, and the drying isn't too rushed. DON'T paint above 90deg, paint dries TOO fast then.
On the maintenance side, sounds like you're the perfect owner! Staying AHEAD of problems is the cheapest maintenance.

Before a repaint, check how much "chalking" your paint is presenting. On the south side of the house, wipe your hand across the siding. If white powder is apparent, the binders in the film have degraded enough to where the pigments are releasing. This will usually be worst on the S and W sides...where the sun slowly destroys things the fastest!

Using a pressure-washer (keep the tip a FOOT away!!!), and a good siding cleaner, wash and rinse your house. Let dry. Chalking/other dirt HAS to be washed off for good primer adhesion.

Use a TOP-quality primer on all surfaces after you've done the necessary feather-sanding/scraping of weaker paint areas. Then TWO coats of new color.
Every 10-15 yrs. is kind of an average for a repaint. No matter how good the paint was/is, colors fade some, etc, etc.. Usually people tire of a color-scheme by then anyway!
Good luck!
Faron

Our house was cedar sided when we bought it, and needed a coat of paint badly. Between house and garage, we had a pretty large surface area to cover, so we gathered a huge crew of family/friends and made a 'painting party' out of it. Everything was all set for a specific weekend in early July (good painting weather here, dry and high heat/humidity doesn't tend to hit till late July/early Aug.) We had everything ready, everyone planned to be here, and with little warning the day before the heat shot up to near 90 (a record for that date, if I recall) and stayed there! Since we had everyone here we went ahead with it, painting out of direct sunlight. Huge mistake. That paint didn't last 5 years before it started to develop fine hairline cracks and spots where it wanted to blister. We've since gotten vinyl siding. Can't emphasize enough: save yourself a lot of grief, do a job like this when temps are not excessively hot and humidity is not excessively high.