Nothing wrong with leaving a windfall for your children but they shouldn't be led to expect it and you certainly don't want your own children to waiting for you to die so they can get their hands on it. Not that I think my children are like that but then again, they probably won't be rooting for me to join the centenarian club either! I often joke to my kids that I'll leave them just enough to pay for my funeral - so they should be pleasantly surprised when my time comes.
What I think saddest of all are folks that spend their retirements living much more frugally then they need to because they want to leave that big windfall for their kids. People in retirement have worked all their lives. They should be able to live fully up to the means that their retirement savings provides for them. I tell my retired parents and in-laws to go ahead and spend it all. Have some fun!