Reno, NV to Fresno, CA route help please

Heading out from Iowa to the Fresno,CA area in a couple of weeks to see some friends and will be driving I80 out to Reno. From Reno Mapquest shows 3 different possible routes with time and distance being close enough that I would consider any of them. The 3 choices are shown as CA-99, I-5S and CA-4. Traveling with a truck camper, my wife and 7 year old grandson if it makes a difference. My only preferences are I would like to avoid very heavy traffic if possible and Vegas type heat.

Also looking suggestions for short stops along I80 to break the trip up and to entertain the grandson.

Thanks!