Not sure if to leave them with granny for a couple of days and pick them up once we've moved or whether 5 year old will find it unsettling and better to include in the move and see us packing up and leaving our old home.
My parents left me and my sister with our grandparents when we moved house, although that was 25 years ago. I was 7 and little sister was 5. I don't remember being freaked out by it, I am sure my parents loved not having us under their feet. When I am finally able to move I will be leaving my dc's with their gp's.
We had seen the house a couple of times though, so it wasn't a suprise when we finally moved into it. Have your dc's seen their new house?
If your children are used to being with granny (and you've explained all about the move and what it involves) then I think it's best all round to leave them with her; my parents left me with my cousins when they moved house when I was five, and I had a whale of a time, while my parents were able to deal with the move in peace. You'll find it much easier to deal with the stress of moving if you don't have little people under your feet. If we ever move again I'll definitely be leaving my two with their grandparents.