I have 2 pairs of boots I wear in the winter: a pair of riding-style winter boots (not quite knee-high, I wish!) and a pair of booties with about a 1 1/2-2-inch heel that are halfway between sleek and chunky so work in either direction. Both I got from Sears (my size makes in-store shopping depressing, and with Sears returns are painless). The booties are Clarks and were a wild card-- I was looking for a replacement for a Doc Marten style boot but these have been SO versatile, and have de-frumped a lot of outfits.
Anyway back to your questions. I wear both pairs with pants (skinny or wide, tucked in or overtop, according to my mood) and with skirts and dresses (pencil/tube or full/A-line). I check the full-length mirror to decide which length works best. I will wear them indoors when they complete an outfit; they certainly are left on for church. At work it depends how hot it gets and whether the roads, and thus the treads, are full of sand and salt. I can happily walk for several blocks in either pair in dry or snowy conditions. Mud, not so much (but unavoidable at times, see: my driveway in spring. Which is why I also have a pair of Land's-End duck boots, thrifted for that purpose.)
I wear them in winter, and in fall, and in spring as long as I absolutely have to, but as Suz said in a recent post, our mandatory boot-wearing weather is so long already that I don't want to waste a single day of our warm season(s) on boots if I don't absolutely have to!