Here's a good stat for you - 6 million adults in the UK suffer with some form of incontinence! No idea how many kids wet the bed but I'm certain you aren't alone.
Not quite in the same boat as you but we are working through it. DD is 6 years and pees right through drynites. Doc says she will grow out of it, but when we were reading we found out that like Tuhlulah says, some kids never really grow out of it.
ERIC is definitely the place to start if you haven't been there yet. Tons of useful information about bed wetting etc
I found a blog post about getting bigger nappies, which helps her loads because although she wears them (which she wasn't too keen on to begin with), she doesn't have a wet bed in the morning! (or in the middle of the night).
This doesn't really help your 11 yo I guess because you didn't say anything about leaking, but it seems to me that most of the stress of bed wetting is the disrupted sleep and wet sheets rather than anything else. An "adult strength" product might help him feel a bit more confident if nothing else.
We are just going to wait it out till she stops on her own, but anyone having dramas with leaking pull-ups should take a look, we were so happy to find anything that helped: www.everynappy.co.uk/blog/size-7-nappies-for-bigger-or-older-children-bigger-nappies-compared
For sleepovers they also have a washable pull-up, they look like normal kids pants but waterproof. I got a pair and they really do look like girls knickers (they have boys pants too) but we didn't try them out in case they didn't work. I think it would be worse if we sent her to stay over somewhere with her "normal" pants, and they leaked! We'll need to do some testing at home first. Largest size is 10-11 years, www.everynappy.co.uk/childrens-incontinence-products/kylie-washable-incontinence-pants-for-children
Good luck, hope that helps!