I'm partial to Matelasse coverlets. They're washable and heavier than a sheet and lighter than a quilt or bedspread.

The Vermont Country Store doesn't have the summer weight quilt, but they do have a lot of different lightweight bed covers and bedspreads.

Here is a link that might be useful: summer bedding

I found a summer-weight quilt at Walmart, of all places. It's the perfect weight for our climate and was most affordable. I purchased it online. You might want to check there.

Here is a link that might be useful: Walmart summer quilts

I use a down blanket in the summer. I got it on sale at Target. I have one in each room. It is the perfect weight for us down here in the deep South. And if we get an especially cold snap in the winter, I use it in addition to the down comforter (makes for very lightweight but extremely warm covers). Bear in mind, my down comforter is pretty light weight too, because it is never that bitterly cold here...or at least not for long.

I also have a matelasse coverlet, but it is much heavier than the down blanket. It is packed away.

Here is a link that might be useful: Woolrich down blanket at Target