I have 2 really social little guys in the mix of my 3sons, and they love informally talking about/sharing/showing their work to each other over lunch. It's neat they are doing different guides, as each child gets to shine as they share.

I just hang their work on the fridge, and they often comment on each others' work to encourage one another. Sometimes it's just 'Can you make this Egyptian pastry again - wow, it's good?!?", or "Did you write your work in cursive today? Man, that looks about as good as mine already!", or "Did you do some finger painting today? Bet that was fun!", etc. LHTH only takes about 20-30 minutes to do, so your 6 yo will only have to fly solo for that amount of time, and that's probably healthy to encourage. During these independent times, each child kind of does what they are interested in. Some of the things for our kiddos have been color by number pages, erector sets, gardening, baking/cooking, origami, folding paper airplanes, exercise - calisthenics or running an obstacle course of their own making outside, latch-hook, paint by number, reading, flight simulator computer program, making smoothies, circuits sets, lego or Knex creations, RC vehicles and designing a mini-course for them to drive through, kick back in a bubble bath and read, write a cousin a letter, organize an area that needs organizing, hydraulic set, or just play with toys! My 5 yo last year enjoyed working through stations...
My post about learning stations for Emmett:
viewtopic.php?f=6&t=10565&p=76777
Hope something here helps out, but one of my very favorite things about homeschooling in general is finishing earlier and having our dc have time to foster hobbies and interests of their own! It's not always easy - sometimes they just want to be told what to do - but it's in the choosing that they find what they love, though it may be sometimes just for a season. It's also in the choosing that they realize getting to free time is golden, because they actually have found some things of their own they want to do - very motivating! HTH!
In Christ,
Julie