Thanks to everyone for their comments and suggestions. I'm going to get the "Wine Safeguard Reusable Bottle Protector *2-Pack" that is listed on Amazon.com. I checked with the friend who originally recommended the Magellans Bottle Armor to me, and he said it's the same product with a different name. He's used his for years and never had any breakage or leaks (he's actually in Italy right now with 3 of the bags).
But no matter how good something sounds, you still have to use good sense - like putting any bottles in the middle of your suitcase surrounded by clothes and not next to each other. Just for added piece of mind I think I'll put each one inside the bottle bag, and then inside a large ziplock freezer bag. My husband loves a good peaty Scotch, but Laphroaig scented luggage and clothes would be a real mess, not to mention expensive.
And yes Laura, I always declare every bottle I bring back and never had to pay for that extra bottle I couldn't resist at the duty-free shop.