UGGs Brook (tall) or similar lined boot?

[buttercup]

I am about to cross the Rubicon when it comes to boots, clearly. But I moved 2 zones north and while I continue to wear my beloved Canadienne's daily, I think I will need something toastier for the mid-January commute.
Are these very bulky? Any other similar boots you would recommend? I hate hate the bulky Ugg look; I think only very skinny people can pull that off and I am not very skinny (size 4 ish if the sun is shining).

[Piglet]

If these are like mine - Brookfield (http://www.superlamb.com/ugg-brookfield-tall), the toe isn't lined with sheepskin on top, just the insole is sheepskin and the shaft. I would confirm that they are in fact sheepskin throughout. If the Brooks are fully lined, then they look like they could be a great choice!

I am in Canada and the Brookfields are my "temps slightly below freezing" boots. Any colder than that and I switch to Sorels. They are not pretty (well, my pair is patent), but they are sturdy and warm. What kind of temps are you dealing with and how long are you in the cold? For me, I take public transit and am outside maybe 10-15 minutes most days and it can be anywhere between 30F and -40F over a single winter, so a few different pairs of boots required over the range.