S.G.
Driving an hour is a bit long, but... If you only invited a few close friends and had people carpool I think it is a good idea. You could buy the same CD (a kids beach songs CD) for each car and pack a fun (not messy) snack and drink for the kids. You could also give each driver $20 for gas. If you only inivted 6-8 friends you would only need to take two or three cars plus your own. Have everyone meet at your house so you can pass out goodies and leave from there. You could also have each child sit on their beach towels to eliminate spilling in someones car. I think it would be fun if it were well organized.
I wouldn't mind driving an hour if a close friend of my daughters was having a special party, I also wouldn't mind driving a few kids and another parent.
Don't forget to go potty before you head out!