Cooking Stove Size

[Dan R-M]

Plenty of talk about woodstoves here, and well warranted, but how about [electric or gas] cooking stoves?
In trying to make the most of our space, and use fewer resources, we've been thinking about getting a narrower-than-standard stove/oven. Standard is 30" wide, and they come bigger, too. But there are also 20" and 24" models out there for apartments and stuff.
The thought is that we don't often use all that oven space or stovetop space, and that, presumably, one would use a lot more fuel to heat the whole standard oven's volume (whether you're making a cupcake or ten loaves of bread) than you would in a smaller one.
But I don't know if that's really true. And from my cursory search, the narrower oven/stoves don't look as high quality on the whole.
Has anyone else wrestled with this question? Better yet, does anyone have experience they could share about smaller oven/stove setups?