I'm a First Lite guy and use the base layers all year. I run the Llano tops for movements during the fall on those chilly mornings and use the Chama hoody as a second layer when I stop. I have both the Halstead fleece and the new Kalamath fleece that I have used as a third layer as well, but normally I will have a puffy on by that point.
Usually I will use the Chama and the bottoms to sleep in at night, until its later in the year and there's a significant amount of snow on the ground and then I will switch to my EXP top and bottom for sleeping.
I have a sawtooth jacket from First Lite, but I haven't really found a use for it. Same goes for the fleece pieces. I have them as a back up I guess, I am still working through what the best use for them is.