For my 4 year old, the only thing I've been able to find that absorbs enough to hold him all night and yet still dries are pockets. (I don't know how much your kids pee, but my DS is a super-heavy wetter, so if I tried to use anything where the cotton/absorbant part is built-in, it takes too long to get dry.) www.snap-ez.com makes kid-sized side-snap (so you can pull them up/down) night-time pockets that are wonderful. Too expensive for me to buy more though, so I have one of hers and drafted my own pattern (for only our use of course)...
Ours are PUL outer/micro inner stuffed with hemp, but you could just ask easily make pockets with all cotton, stuffed with cotton, and covered with wool. Actually, I'm going to be doing that soon as well, we're having wicking-onto-cotton PJs problems with the PUL/micro. I just ordered an XXL/child sized aristocrat, so I wish us both luck!
Oh, no real advice on a pattern though, sorry... I didn't have much luck finding one myself.
Ours are PUL outer/micro inner stuffed with hemp, but you could just ask easily make pockets with all cotton, stuffed with cotton, and covered with wool. Actually, I'm going to be doing that soon as well, we're having wicking-onto-cotton PJs problems with the PUL/micro. I just ordered an XXL/child sized aristocrat, so I wish us both luck!

Oh, no real advice on a pattern though, sorry... I didn't have much luck finding one myself.