Katie,
It is so hard to find a writing program that we love for the age you listed! We did the writing lessons out of Intermediate Language Lessons for grade 3 and 4, which we actually did like fairly well, yet there wasn't much guidance in the lessons. We did not use the grammar portion of ILL, as it required much discussion with me.
If you are using Rod and Staff English on grade level, or one grade below then there is more than enough writing in there. However, since we switched my oldest to Rod and Staff after going through several other programs that didn't stick, we are "behind" in Rod and Staff (meaning the writing lessons were not quite enough).
Then in grade 5, we did Institute for Excellence in Writing Level A, doing it only twice weekly. We liked it fairly well, as Andrew Pudewa is quite entertaining. But, this year in grade 6, as we moved on to Student Writing Intensive Continuation B, we hit a wall in January. It was just way too formulistic for my very creative first-born and seemed to be sucking the life out of writing for him. So, we paused. Not to mention it was incredibly expensive - $200, which I cannot justify spending on writing.
We had been wanting to use "Igniting Your Writing" which we really love (and carry), but we were waiting until my son could do it independently, as teacher time is at a premium here, so that's why we did IEW SWI- A and now IEW- Continuation B (on DVD).
All of that to say, we will be writing our own writing lessons into "Preparing..." twice weekly since we are unable to find exactly what we want for the age 8-10 range. We do like Igniting Your Writing the best still for grades 5 or 6 on up, yet you need a child old enough to work through the lessons independently (or you need the teacher time to work with them).
Susan Wise Bauer's new book "Writing With Ease" (which will be out the end of May) does use an approach that appears to be closer to a Charlotte Mason approach to writing than most, yet it looks as if we have already covered the writing skills she will be using in her Year 1 and 2 in "Beyond..." and "Bigger..." through oral narration, questioning, copywork, and studied dictation. It sounds like we also will be covering the skills in her years 3 and 4 with "Preparing..." through oral narration moving to written narration, dictation, questioning and continued copywork. We will take another look at Susan Wise Bauer's next level of Writing with Ease for grades 5-8 when it comes out, however, it appears that will be quite some time in coming.
I'm sure this was not helpful, but writing is one area where there is precious little that is good for the younger years. So much is twaddle, and we have looked at, or own, just about every option out there!
If your kiddo is not quite up to "Igniting Your Writing" and you don't have writing covered with Rod and Staff, you could do Just Write Level 3. It does a pretty good job in applying the different forms of writing in a worbook form. It does have a couple of semi-controversial topics close to the end of the book. But, it is worth a look.
Blessings,
Carrie