5 hour drive from Vegas to the south rim.
You may or may not get the helicopter ride from Vegas in May, start making reservations now.
Williams Arizona is an hour and a half from the south rim, and there is a train from there. An old steam train like petticoat Flagstaff is two hours from the south rim.
You won't get reservations for a south rim hotel this close to may, well it's highly unlikely. Same with whitewater trip, and mule rides.
The north rim usually isn't open until late may or even June.
We have had a lot of snow so far this year, the north rim is higher elevation and some years the snow doesn't completely melt. Usually the roads open in may or June, but check before you go. The north rim is 4 hours from Page az, 9 from Vegas.
May is windy here, bring warm clothes. I carry goggles in the spring so the dust doesn't fill my eyes. May is fire season, I know it sounds odd to easterners, but the park stays open if there is a fire. It's an impressive sight, but use common sense.
The grand canyon is one of the most visited parks in the world, it's busy. Also one of the most heavily patrolled, people don't disappear. That's myth. If that sort of this interests you, a book called "death in the canyon" documents all known deaths through 1992. Interesting read. Turns out most deaths of tourists are while taking pictures. (One more step back honey)
Enjoy yourself.. and welcome. In my youth I worked at bright angel Lodge and at the stables. Been all over that place. Grew up in Burnsville though. I live near st Johns az now, been here 30+ years.