You may never need anything more than the neutral collection as these five colours cover all eventualities. Bet you're a squirrel like me though. If you are then you'll love collecting every colour of thread. You will enjoy the Pat Campbell Romance Collections. These assortments are the perfect colours for her quilter's fabric line "The Romance Collection" from Timeless Treasures and for any other appliqué project you come up with.
Both collections from Elly Sienkiewicz are gorgeous for heirloom appliqué work.
And there more colours to lust after with three Jeanne Sullivan travel sets. Plus all the variegated 100% silk thread colours and the Silk Sparkle collection.