Spectrum workbooks

I’m needing a summer supplement for writing and spelling. The Spectrum workbooks seem to fit the bill, but I wanted to see if anyone had other similar suggestions. Here is an example…

http://www.amazon.com/Writing-Grade-4-Spectrum/dp/0769652840/ref=pd_sim_b_3

I absolutely love the “Key To” math workbooks, but there is none for language arts! The above is from the same company I believe.