This is quite a fun and retro style I've found on Molly Flanders blog, she mixes machine quilting 1/4" from each seam and the uses pearl cotton or other thick thread to do chunky hand quilting, often in a contrasting colour, to give more interest to the quilt.

http://mollyflanders.blogspot.com/20...spart-one.html

But if you want to do machine only I just love it when you quilt across the block, like a diagonal grid across a square quilt so you get diamonds