K12.com
We've used K12 for five years, but as independent HS'ers, not through a virtual school/academy (like CAVA).
I love the depth and breadth of the courses, especially in history and art! My son loves them, too! The entire scope and sequence of K12 is amazing!!!
The online planning and progress tools are *so* beneficial!! I also like the online activities that balance out the text/book work. Unlike what someone said, it's not lots and lots of worksheets. You do not have to make your student go through every part of every lesson. It's like a buffet - you take what you need/want (to master the lesson & unit objectives) and you leave the rest. It's a mastery-based curriculum, so they test mastery - usually every lesson, or at least every unit.
I don't know what grades you're looking at, but we've done most courses from Kdg to 8th grade (currently Advanced Physical Science). I can answer any questions you may have.
Also, not to be technically correct (like my engineer husband!) but using an online "program" (I think you mean CAVA) is *not* homeschooling. It's using a virtual *public school*. Parents who use K12 via a virtual school have to know they won't have the freedom that independent HS'ing does (like me). You do have to conform to the school's progression rate, schedule, and testing requirements. I know many people who use K12 virtual schools and love them. Others don't want to be restricted. That's where we're at - my son can't be restricted to only advancing two grades, which is the limit of some virtual schools. So we purchase K12 on our own just like buying any other curriculum: Abeka, Sonlight, BJU, etc.