I would do what Peckish says, buy some samples and see how you like them. Harriet Hargraves sells batting squares, and her shop is in Colorado.
You didn't say if this was hand or machine quilting. If it's hand quilting, I can recommend Hobbs Polydown - it has a bit more loft than other battings.
As for thread, that really depends on how you're quilting, too.
Janet