This is our first year homeschooling and we are using LHFHG with BLHFHG Spelling for newly turned 7 yr. old ds. We are also using LHTH with some K material for newly turned 5 yr. old ds.
I have added some extra Science to our days. The LHFHG Science is very simplistic and my boys love Science so I wanted to add a bit more "meat". We've added Apologia Astronomy which we love and many library books, such as the "Let's Read & Find Out Science" books and DK Encylopedias. I don't feel it's necessary to add to the LHFHG Science though.
My thoughts on the rhymes: There are a few rhymes sung to the tune of very childlike songs such as "I'm a Little Teapot". My ds did not enjoy that one! We normally don't do the rhyme every day; 2-3 times per week is enough for my ds.
The LHFHG devotional is perfect for my oldest ds as he is doesn't require much visualization. However, I'm going to wait and use the devotional with my youngest ds when he's a bit older. I don't think he would understand much of it yet.
If your using LHFHG with a 5 year old, I would recommend using the Family Time Bible rather than 101 Favorite Bible Stories. We've used the latter this year, and enjoyed it immensely, but not for a young K.
I chose to use LHTH with my younger ds as I knew he wasn't ready for LHFHG. While he already knows his letters and their sounds, he has still really enjoyed this program. The Bible story and related activity is wonderful. He balks at the Dramatic Play and that's fine with me.
As to combining children, I believe the author suggests choosing the guide that suits your youngest rather than the oldest. You can than beef up the guide for the older, if needed.
As already suggested, I would definitely recommend getting your hands on as many guides as possible before buying.
Blessings,
Jess