Your toughest pass will by Raton at the NM/CO border. It isn't too bad however. You should find this to be an easy leisurely drive. There isn't much but wide open spaces from Las Vegas to Raton, try not to go to sleep. Can't say if there will be an road construction issues or not. There is almost always some construction on I25 around Albuquerque, it is a tradition there. Pueblo CO is where I25 gets kind of crooked and dangerous, just take it at the speed limit and you should do fine. We welcome you to COS, lots to do around here.