I too have a similar situation. We have a 10 yo dd in public, 4 yo dd and 2 yo dd. The 4 yo will be ready for kindergarten this fall according to our county in MD. She likes to work in preschool workbooks sporadically and independently while I watch. She does not permit much suggestion or instruction however (she cannot read and tries to guess what the instructions are for each page). She also becomes frustrated with explanations and books without pictures (she puts her hand over my mouth and shakes her head no if she finds the story boring). My 2 yo is a sponge who picks up everything I try to teach the 4 yo.
I have found that leaving her alone with the workbook thing was best. The day before yesterday she did allow me to show her what to do with different sections (circle the group with less/color the triangles, etc.), then worked by herself for 15 or 20 minutes. Also, I have found that memorizing some stories (three billy goats gruff) and retelling at bath time, or some other time than bed time is alot of fun. She thinks its fascinating and is not dissappointed that there are no pictures. After one telling, I am commanded to retell it with her changes. It then becomes a whole new story. Very fun.
My goal is to homeschool all 3 this year and I have been on a research binge. Curriculum, curriculum, curriculum. Mostly the structure for my soon to be fifth grader is sought. However, I am always looking for content for my 4yo.
3moms.com offers a curriculum fair in a box. I think it was about $30.00 and you identify what level you need. That may be a little pricey for samples, but, for a new homeschooler as myself, I thought it was helpful. It came with 6 or 7 samples, with alot of backround information fleshed out for easy reference. Most were Christian, with one or two secular. I have found it helpful in deciding what direction to go in (unit based sounds best for my family, interesting and inclusive).
Good luck!