I would recommend going to The Container Store and browse there. I'm pretty sure you could find something there that would be suitable - I've gone there for a few things myself.

Personally, I use an old very large plastic mayo jar, and it will hold about four pounds of flour, and it has a huge lid - large enough for me to get a one-cup measuring cup inside. I have also saved some "snack" containers that previously held huge quantities of rice crackers or other snacks. Some are square and some are round. They also have screw on lids. They look something like this.

Unfortunately, it is difficult to replace the old Tupperware - the new isn't as good, but sometimes you can find it on eBay.

I used to use large glass jars for a lot of storage, but after the 1994 quake (which made a huge mess in my kitchen), I have switched to plastic, and so I understand you need for unbreakable. I prefer something that is at least somewhat see-through as well, and the mayo jars are perfectly clear.

Just get Tupperware again? Or, here are a couple threads with lots of recommendations and links. I suggest you look at Cambro storage first, which are pictured here (not my kitchen):

http://ths.gardenweb.com/discussions/4480487/flour-sugar-etc-storage-in-drawers

http://ths.gardenweb.com/discussions/2492068/seeking-new-canisters

I have the Oxo square plastic canister (for my flour) and am satisfied with the looks and function. It has a clear base and a white push button lid. You could probably drop it hard enough to break it, but it is quite sturdy. This canister comes in different sizes, but mine holds a 4-5# bag of flour. I also have one for sugar. I think I got mine at B,B & B, but you can find in many stores. Might be work a look.

I also have some of the OXOs though my favorites are ClickClacks with the pinch. They're different versions of the same thing--they use pressure to make the tightest seal. Clear (for in a dark drawer or cabinet--use something opaque if it's going to be in the light), food safe, light weight. If you drop them while full they can crack but don't shatter. Easy open and close single handed. OXO lids are a bit easier to disassemble and clean, but need it more. ClickClacks have a better seal, but it's very close--both are pretty airtight. Downside, they can etch from sugar crystals and the like, but not enough to get cloudy. OXO takes up more space because it bulges out more around the lid. Both are stackable. They both come in a variety of sizes.

I have some decorative ceramic and tin and some restaurant containers and some tupperware. By far and away it's the ClickClacks and OXOs that win the day for pantry storage for me.

I don't think those Cambro containers are airtight.

FWIW, I prefer tins - they don't crack like so much plastic stuff usually does. I prefer a more eclectic style, too; I have a collection of large vintage decorative tins that I don't hide away.

I don't empty the packages into the tins either, since they are large enough to hold several different bags of flour or sugar, etc.

I like the Rubbermaid 6 qt Square Containers from Sam's Club. They are located in the restaurant supply section or online. Perfect for 5 lbs of flours and sugars. I used my P-Touch label machine to tag them. I've used them now for 8 years and still look brand new. They are 2 for $16.98 at Sams including lids.

I have a Tupperware container that's at least 35'years old. Hubby wanted to get rid of it because it's an ugly lime green colour. I'm so glad I didnt, especially after reading this post.