Yep somewhere floating around here there's a thread about it. Basically you have three options.
1. Just assume that you'll be about replace you collection with the insurance you have.
2. Get a rider that covers you for the cost of replacing a specific dollar amount. Which is easy, and what I did.
3. Get a rider that covers you for "collectors value of the collection with replacement of collection". This basically means you have to document every set and possibly get it appraised. Because if lose a UCS MF, UCS SD, UCS Y-Wing: they give you the money to replace those items at their current cost.
I went with option 2. I simply input all my purchases into Brickset. Brickset was missing info for some sets, I did some basic math to get the average cost of set at time of purchase and then get the collection ensured for that amount.
So just as an example:
Option 1 would give you $30,000 to pay for all your personal items in the house including major appliances.
(Note personally this is good for people with collections from $5,000 to $10,000.)
Option 2 will give you say $25,000 on top of your $30,000 for everything else, however the $25,000 has to be used with 12 months to purchase only Lego. And you'll pay $5-15 more per month (Or more, or less, depending on size of collection.)
Option 3 will give you a blank check to replace the set by set cost of your collection but it will cost you $15-30 per month (and of course this would vary based on size of collection).
And PS: Yes I live in Ontario and I use State Farm Canada.
Yea, though I walk through the valley...