We are using the Macmillan/McGraw-Hill reading series "Treasures." I have posted two levels of spelling lists for grade 4. Treasures calls them level O (for On-level)and level B (for Beyond.) I call level O "B" for Spelling Book list, and level B is my "C" for Challenge list. The lists are available in the Navigator.
I had to make up activities for the Challenge list people, but SpellingCity gives them more than they can possibly use for practice. The activities are varied enough so each student finds something they like. I still hand out my word search, crossword puzzles, word shapes, and unscrambles to the kids.