I have a couple of these Rubbermaid Lock-Its. I've never dropped them, or tested their durability or security, but they seem pretty effective. Airtight, and they're kind of difficult to close- which makes me think they're probably pretty difficult to accidentally open. Not exactly good looking- but functional.
http://www.rubbermaid.com/Category/Pages/ProductDetail.aspx?CatName=FoodStorage&SubcatId=BulkStorage&Prod_ID=RP091550

Have you looked at the all-clad canister? Expensive and a bit heavy, but these are really solid, the lids seal very well, and so far they have not dented when I drop them. Its unlike me to buy something so expensive, but five years later, I'm very happy with this purchase.

I have OXO Pops, and they don't come open, but they can sometimes (but not always!) crack when they hit tile. They would probably be OK falling onto a counter or not so far.

They are better looking than most solutions, and you could probably configure them so the cat couldn't get on the shelf anymore.

Hard to find but I like Aero Housewares brand which are food safe plastics with a screw lid and had containers that could hold 10lbs. Unfortunately they went out of business in 2008.

Have you considered buying plastic containers at your local BJ's or Sam's Club, etc., which have snack stuff like Utz's Cheese Puffs or Snyder's Pretzels? these things are huge screw lid containers that can be re-purposed into storage containers (for free). I use them to store rice, and flour (specialty rices like Basmati are cheaper in larger bags).
If you find these too big, store them in the closet and get smaller containers like those used for Rice Selects for ready access on the shelves. The Rice Selects brand even have good hand holds built-in and are square which means that you will fit more of them in a small space.

Frankly having lived in a brownstone in NYC, everything should be stored in something (even boxed goods in a huge baggie) to deter pests.

I agree with RB43. The OXO Pops are wonderful! They can be a little pricey, but I think they're worth it. Check TJ Maxx, Homegoods, Marshall's, etc. for a better price. I am able to find the containers are those stores occasionally. Otherwise, Bed, Bath, & Beyond has them.

I use large glass canisters (I think meant for canning) with metal clasps and rubber gaskets. They stay tightly sealed and everything stays incredibly fresh! Mine are actually hand-me-downs from my mother's semester abroad in Italy and after almost 40 years they STILL don't have a single scratch or crack. Something similar: http://www.amazon.com/Bormioli-Clear-Square-Canning-Liter/dp/B0001BMYHA/ref=pd_bxgy_k_img_b

I have a couple of large plastic "Lock and Locks." They won't come open, but I would imagine anything plastic would break with 5+ lbs onto tile.

I don't mean to sound judgey, but maybe finding a way to keep the cat off the shelf is more important. It would gross me out if I was eating in your home and saw cat hair on your food containers :(

Try King Arthur Flour, the storage bins come in different sizes and will fit a bag of flour. They are affordable as well. I don't know how well the top will stay on it the container falls on the ground, but it fit tight enough to keep bugs and moisture out of my flour and sugar.

click-klack all the way! I love them!

These seem a little more pricey, but they work really well. They are very sturdy and the lids are very secure and tight.

All Clad also is another pricey but sure way to go. For a tighter budget, I've heard good things about this set.

Before my current method, which got pretty because I don't have the issues you're dealing with, I used the Click-Clack and they do work really well. I'm a klutz and the times I dropped one the lid held tight, which was great, once when I dropped one it did crack but did not break open... I think those are your best bet.

I have the rubbermaid modular canisters, and they are air thight and resist being played with from my 1 year old.

If looks are not an issue, try using the containers for whey protein (GNC etc). They can easily hold a 5 pound bag of flour/sugar, have screw tops, are opaque (helps with freshness), and are kind of flexible so won't easily break after a fall. Probably too expensive to buy the protein just for the containers but will help if you have friends who use whey protein.

SNAPWARE. They have a lifetime guarantee, no questions asked. Airtight, come in all kinds of sizes and shapes... They're perfect.

I use the ones from King Arthur Flour and I adore them. I only have two small ones right now (for AP & WWW flour atm) but when I have a bigger kitchen, I'll get more!

Perhaps you could velcro your current canisters to the ledge?

These cereal keepers are what I keep my flours, sugars, and rice in. Holds 5 lbs of flour, easy for scooping, snaps tight.

We use the round tupperware bins my parents bought 30 (million) years ago. Large, sturdy and they're pretty hard to tip over.

Love my Tupperware containers, and they have a lifetime warranty, so if they break, you can get them replaced. (I actually have two sets of their canisters--old school canisters bought at a thrift store and new ones I ordered when I couldn't find the old ones after a move--but then I found the old ones. And I'm thrilled to have two sets.) My cats have been jumping on mine, too, the punks.