I would ideally like all of my kids to follow the same curriculum to save me money and to save me from having to keep figuring out new systems.
This quote made me think you might want to look into Math on the Level. While it isn't cheap (around $300 new), it is for preschool through Pre-Algebra, which for our oldest is turning out to be 8th grade. For some children, that might be 6th grade or somewhere in-between. Point is you can use it to teach all of your children all the way up to or through middle school years. So when you figure it out pricewise that way, it is very reasonable. You don't need anything else with it, because it is very thorough.
NO worksheets and not pages of endless problems. You can add in extra review if you need to at times, but each day you use a paper called a "5-a-day" with five problems. You can gage your child's abilities with this paper, and you can see their mastery (or not) by giving them problems of your choosing, which may have more than one skill in them. Once mastery is achieved, you don't put those types of problems on anymore unless you want to.
They have 4 books divided by these major math sub-topics: Operations, Fractions, Money & Decimals and Geometry. With the complete set, you also get a Math Adventures book and Math Resources book as well as acess to a free on-line excel worksheet for keeping records on each of your students.
They have a yahoo group that you can join whether you own the products or not. It might be of interest to you.
And finally, they have a 30-day trial, where you can try before you buy. The family who developed the program have two DC graduated from homeschooling and 1 still in high school I believe.
I have no affiliation with them, just finally found a program that works. It isn't magic and my DC who struggle in math still struggle sometimes, but they don't end up in tears and they are learning new concepts all the time.
Here is the general website: https://www.mathonthelevel.com/
And a link to the yahoo group: http://tech.groups.yahoo.com/group/mathonthelevel/
BTW, I have 5 children ages 6-13 in the program, grades 1-8 officially and I fully expect to use it with DD, age 2, and with all of them through mastery of Pre-Algebraic concepts.