Visiting RMNP in May/June

I’m trying to plan a trip to denver and to see RMNP,I’ll be driving from Kansas.It would be me,my wife and our 3 year old,what should we expect as far as weather and traffic coming in one of those months?Were planning to stay 5 days there,what are some must see things that are in the Denver and RMNP area that’s doable with a toddler? Also what town is best staying in,besides Denver thats close to both location that’s not a far from drive between the 2?