My dad and I used to talk about this all the time - I think we decided that we would need to win $12-15 million to do what we wanted. We both agreed that we would do a little splurging to get it out of our system, and then invest the rest and live off the interest.
I would first hire a lawyer and financial planner. I want to help out my family, but I would consult with the experts so it wouldn't cause any tax issues (IRS gift tax, etc). Depending on what they say, I would pay off my parent's house and grandparent's houses, put my youngest brother through college, give my middle brother the equivalent amount of money. We would probably just give DH's parents, grandmother, and brother money, since they have no debts.
I would buy a new car (Dodge Caliber), and quit my job to go back to school to get my MLS - then maybe work part time as a librarian. I'm not sure about DH. He'd probably quit his job, set up a woodworking workshop and do that part time.
We would travel - there are a lot of places I want to see. We would finish the work we want to do on our current house (dormer the roof, redo kitchen and bathroom, finish the basement), but we would hire someone else to do it! Then we'd probably build a house on my family's land, and it would include a barn so I could have a couple horses. I would buy an HDTV, and finally get all those premium channels I've always wanted to watch! I would get an Ipod since I've been wanting one for a while, and DH would get a brand new top of the line computer for his gaming.