My LO broke out of EVERY swaddle we tried (we tried 6 different products before finding what worked). No matter what blanket we used or how we swaddled, he'd break it and have the blanket over his face in no time. The sacks didn't work because they weren't tight at all and he still startled awake.
What finally worked, gave me piece of mind, and just over all rocks was the Woombie! We started out with a small one, then moved to the big baby one that we just stopped using last week. *tear*. We used the basic summer one and always dressed him in a footed sleeper underneath it. He loved his woombie so much. We only had one of the small ones and I ended up washing that thing ALL the time so I really wish we had bought two so we could rotate, but never did. We DID buy two of the big baby ones and that was great.
If the woombies are too expensive, the Swaddlepod is essentially the same thing, the fabric isn't nearly as nice though, and they are often too short. The woombies are extra long to make up for taller babies.