What are things you do to reduce clutter in the living and dining area? Now that everyone is home, its always a mess since the kids and DH don't ever put back any of the stuff they take out. It just drives me nuts, and was wondering if anyone has any ideas.

You could be talking about my place. Our place is so much messier now because everyone's home. It drives me nuts that nobody puts anything away either, and I'm working so I can't be monitoring my kids all day saying "are you done with that? then put it away." I took some time this summer to get rid of a bunch of stuff -- took two carloads of stuff to donate. So freeing. I've made new easy storage spots for stuff that always gets scattered everywhere -- like a big basket to hold all their drawings and writings that are otherwise scattered over the dining table. So periodically just grab all that stuff and put it in a basket, and go through it every so often. Better than nothing. Trying to have them do daily pickup while I make dinner.
Ditto the basket and juat be sure you have the strength to empty it regularly! We got one per person for mail and lost bits, and put them along a sideboard, and now they only get emptied at big seasonal cleaning moments, not daily or weekly. Not sure we improved things.
I learned that decluttering is a constant battle. The work is never done.
Stuff has a life of its own, and it will take over like kudzu. Our apartment has totally jumped the shark -- we're making goat trails through the clutter to get to the bathroom.
When I can, I definitely stay after my 9 year old to pick up his crap. I think I just get so sick of stuff always being all over the place. But I also set the timer for 5 or 10 minutes every day or so and force everyone in the house to clean an area - just till the timer goes off. Kinda dorky, but you can actually get a room looking somewhat decent in 10 minutes.
I do something similar to this and agree it works well.
I'm super tidy and DH is a pack rat at best. You have to be on top of clutter at all times, working with DH to declutter regularly helps too, he appreciates tidy spaces but has ADD and is utterly incapable of achieving that without massive help. My go-to move is to get rid of things, donate or give away or trash, that's really important too -- not all clutter is made up of things worth saving. Basically, for me it's a lifestyle to be tidy.
I'm jealous that your DH is appreciative at last. My DH is resentful of my tidying/de-cluttering efforts which makes ME resentful and angry.
Make it easy to keep things neat -- everything should be in its place, but everything needs to have a place for this to work. Invest in organizers if you need to, and try bins for each person and just toss their stuff in there if they don't put it back. When bin is full, it goes in the trash unless it's been cleaned out and things put back in their proper place.