We were there this April and we had snow. It snowed for two days and we felt it would be best to make accommodation and we stayed in the RV park an extra day. The many people in tents filled up the Kamping Kabins. It was cold, it was wet, and the 5 year old twins had a blast. We still drove up to the South Rim, even with blowing snow it was a great trip in the car. We stayed at Williams/Grand Canyon Circle of Pines KOA, we've been there a few times and I highly recommend the campground. Large indoor heated pool and spa, lovely playground, lots of really big shade trees. Bearazona is another local attraction that should not be missed. It is a drive-through animal park, where you can take all the time you want to slowly drive the large complex and see the bears, mountain goats, wolves, etc at play in open environments. There are many nice (not great but nice) restaurants in Williams, and if the weather is not perfect, and even if the weather is perfect, you can take the Grand Canyon Railway from Williams to the South Rim, walk around or take the trams to see the sights, and then take the train back. Truly we found the Grand Canyon more enjoyable on sunny warm days, but a day or two of snow will certainly not ruin a great vacation.
JMHO
