This would be an excellent thing to be able to do, especially if you were slowly dying of something painful or something brain-erasing like Alzheimer's. Unfortunately American society likely does not allow people the right to do this currently.
Euthanasia by cryonics, or euthanasia in general? I'm pretty certain that euthanasia isn't illegal in parts of the US, and if you're careful you can make it count as suicide.
I'm reposting this from HN's front page, because it brought up a non-cached thought on cryonics:
In short, end-of-life medical care is often pointless, painful and costly; doctors and ER personnel know this so well that they go to great lengths to ensure it doesn't happen to them.
It seems as if our systems and conventions around end of life are designed to not let people have a say in how they spend their final moments, even when letting them have their way would result in significant savings (note the dollar figures quoted above). I've already speculated on why that might be, but I keep seeing that turn up in unexpected ways.
I suspect that this is the bigger obstacle to cryonics, not so much e.g. the lack of scientific proof. "Freeze me cheaply instead of spending insane amounts of money on brutal attempts at keeping me alive" sounds like a sensible thing to tattoo on your chest, but the evidence suggests that it wouldn't be honored any more than "DNR" tattoos.