I like stitching 1/4 inside the blocks. just place your foot on the seam lines and stitch. as far as doing straight lines across a quilt, don't. you can do wavy ones instead. that hides a lot and makes an interesting stitching idea. for that, i use my walking foot and just move the quilt to the left and then right and so on as i quilt across it.
have fun!!

I did SID in a king sized snowball quilt - since I did this on my dsm, I named this quilt "Snowball Fight"! It was a bday gift for my husband, who loves it, but frankly it's not one of my favorite pieces. It's warm any comfy to sleep beneath though....good luck with your quilting efforts!

Thanks everyone, some great suggestions here. And thanks for the pic Hillcountrygal, it helps to actually see how the straight lines look on the snowballs. I might try a combination of a grid but using the wavy line stitch on my machine. I have a walking foot, with a thing you fix to the side so you can measure accurately, but can only use the walking foot for straight stitch or zigzag. If I don't use the walking foot I have terrible problems getting the correct tension to avoid puckering, so lots of options to weigh up! Will try to remember to post a pic when it is finished!

The Frixion pen is great but you must realize that you will never be able to remove the ink. Yes, it becomes totally transparent with ironing but if the quilt is exposed to cold, the lines will reappear. Yes, they are removeable again with an iron but "think of it" - any future owners of the quilt might not realize this. I recently learned this the hard way so made a special label and sewed it to the quilt advising that if the quilt gets cold, remove the markings with an iron. There is no and I mean NO stain remover that will remove Frixion ink!

How about echo quilting ? Tie quilting in the centers and corners?

I Echo Quilt a lot!! Some type of design would be nice in each block also.

I really like that idea