Here are my two suggestions:
Use bamboo somehow, it's really absorbent.
Use fleece as a stay-dry layer, it will keep them comfortable.
Whatever system works for you for daytime, just increase your absorbency for nighttime.
Our nighttime system is a Fuzzi Bunz pocket with a Cotton Babies one-size microfiber insert and a bamboo/hemp insert that originally came in a Mandi's Menagerie bamboo fitted. I have sometimes added a bamboo/zorb insert from a WAHM on nights that she has nursed alot just to be sure, but the microfiber/bamboo/hemp combo has been bulletproof. I have never had a nighttime leak. Never. Ever.
Except once when I used a sposie. Go figure.
(This was one of the first nights in the nighttime system. A little big on her at first!)
Different fabrics have different properties when it comes to absorbency. Microfiber absorbs very quickly. When the rush of pee comes, its good to have some microfiber around to catch it. Bamboo and hemp absorb quite alot of liquid for their weight, but it takes some time to do that. Having a microfiber layer helps to quickly absorb the fluid and distribute it evenly. Having a bamboo or hemp layer helps to "store" the fluid and prevent leaks.
This is also the premise for the Thirsties Duo Diaper's insert. It is a thin microfiber layer snapped to a thin hemp layer.
Lots of mamas also use fitteds for nighttime. There are always mamas on DS touting Goodmamas for nighttime. In a pinch once, I used a Bububebe bamboo fitted with all three insert layers snapped in under a Thirsties cover. It didn't leak, but my Wee One was about 6 months old at the time. Give it a try.
If you're not using a pocket, you might consider using a liner of fleece for the stay-dry effect. If you're using prefolds with doublers, or fitteds, the fleece will help keep the moisture off the skin, which will help with comfort.
About sleeping through the night and cloth diapers - there have been various threads on DS where mamas discuss whether or not using cloth diapers causes their child to wake more at night. My child doesn't sleep through the night, so I can't totally speak as an expert on the subject. Here's what I can say - the few times that she actually slept for 6 or 7 or 8 or 9 or 10 hours at a time, she was in a cloth diaper. I read one of the threads about sposies helping them sleep better and in a moment of exhaustion hoped it was true. I went and bought a whole box of Pampers, and she woke more that night than she ever had.
The key is comfort. Make sure the diaper you use is absorbent enough. Make sure the wetness doesn't stay against the skin. Then you can be sure their night waking isn't about the diaper. (Ours is about nursing and cuddling. I can't wait until we spend more time doing that during the day!)