`12 miles? It's like 7 from the SR to the river via the Kaibab trail, another very easy 7 to CW camp. Very easy 14 total miles, even with 5 experienced rug-rats. I do agree though that hiking from CW camp all the way to the SR would be a stretch for 5 kids... I guess I missed the 5-kid thing. I still think first night at CW camp is doable, with some other alternative for last night, closer to SR, like maybe that clear creek area. I'm just excited about first timers seeing the North Rim trail above CW camp; my favorite trail in the Canyon.
Also: Agree, It will definitely be very cold on both rims at night, precisely why I discourage camping on either rim. Anything low-ish in the canyon should be nice and warm, especially of course the bottom (Phantom and those other places mentioned). Also Cottonwood camp; should be nice and warm there.
Also agree there will probably be leftover snow and a tad of ice on the shaded upper south rim trails. Gone entirely in the 1st mile or so.
Finally: PLENTY of water all throughout the main GC corridor. Plenty of TAP water, in fact. In 14 years running the water in the residence above CW camp has only been off once. We always carry tablets as a backup, used them precisely once in 14 years. The creek will of course be flowing like crazy that time of year.
Shutterbug: we're doing early April this year (2016), it flip-flops from late March to early April. I think this time frame is the absolute BEST time to visit the inner canyon. Tons of daylight and not too hot yet, though we have had 90's at Phantom in early April. Most years it's 80's at the bottom then, very pleasant.