On a larger quilt I pin all over, for reasons others have stated. I like to use long straight pins stuck into foam earplugs. This works great for me. I used to use spray baste, but found it more bothersome than this method of pinning. Here is a youtube video that demonstrates taping skewers to the middle of your table to help you center the layers:
https://www.youtube.com/watch?v=jnke_KzeTI8&t=146s