There are two ways to brew by season - as mentioned, the first is temp. control. If you don't have great temp. control then you want to brew your cooler fermenting beers now and you want to brew your saisons etc. in the summer.
If you do have temp. control, then you want to think about what you want to be drinking 1-2-3-4+ months from now. A lot of that just has to do with what you like to drink - so it is a matter of preference.
*I try to get some light lagers and pilsners going over the next 3 months - because I like to have them on hand from April-August (Pilsner, Helles, Dortmunder.)
* Will brew some sort of Oktoberfest in June or so.
*I will likely brew a Bourbon barrel porter in February . . . . . because it seems best at about 10-12 months old.... so I brew it a year in advance.
*I will brew more amber ales in late july so I have them in september. I will brew browns and porters in August-October so I have them through the winter.
*I brew APA's and IPA's all the time, because those are my favorite to drink.