I agree with the no lamps unless necessary. I have two little ones and while they have never knocked over lamps, I don't have any within reach in the playroom. We rely on natural light and then a floor lamp placed behind the couch that isn't easily accessible. I would do as Tib suggested and put pretty bookends and books on top, or random toys or big ones that don't fit in the cubbies. Love the map idea over the storage. Then I would get attractive baskets for some or all of the cubbies. Then even if they aren't filled, everything looks uniform. I like uniform. : ) Serena & Lily has nice baskets (I have some in my daughter's room) and they are having a 20% off sale in a few days. Land of Nod is also running 15% off bins and baskets right now. Pottery Barn Kids has some cute ones and you can find a coupon every once in a while. Bins and baskets in general aren't cheap but I love the look and function of them. Just make sure and measure your shelves before ordering.

Oh come on! 10 years old and he has to be erased and banished to his room? The OP wanted to renew this room as a family room, not as a formal living room. In my books that means comfortable, welcoming and meeting the needs of the family. In this case, lego is his thing, mom is onboard and that should be the basis of the design plan.

Allowing your children to leave toys all over the floor for hours on end is a trip and fall risk for them, and more seriously for you and your spouse. Certainly there is a happy medium between OCD perfection and pandemonium. Children can still be creative and clean up after themselves and learn the good habits that will help them in school (and life) and to be good guests, even as young children. Habits that are not reinforced in the home tend to not be practiced outside the home. (Table manners are a good example. Yes, I'm 110 years old, in case you are wondering. No, I'm not, table manners are another one of my pet peeves.) I suggest breaking down all the things your kids have into dedicated zones: I'll give you some examples: Lego zone Blocks zone Arts and crafts zone- further broken down by materials, maybe: painting easel area, other arts and crafts, etc Dress-up zone Play kitchen zone Trains and tracks zone So you need to reorganize the room that way into little mini-zones. If you notice, that is the way that pre-schools and kindergarten rooms are organized. Within each zone, items should be in easy to put away containers that are clearly marked with labels if your children can read, or photos if they can't. You can use clear plastic bins that make it easy for them to see what us inside, too, with lids that snap closed, so when they pull things out they are less likely to spill everything. Cubbies and shelves should be at their height. You need to train your child that when they are finished playing in one zone, they must put away everything they used from that zone before they go to another zone. That will take some effort on your part spending some time with them down there, watching them as they go from one activity to the next. Once you have trained them to clean up each area before going on to the next, you can also tell them that at the end of the day or before lunch you will give them a 5 minute (or however long you think it will take) notice to put everything away. (You've already given the 10 minute notice that playtime is ending.) What would work better is if you bought an easy-to-work timer that they could set themselves, so they are in control of it, and you just say, "Okay, Clean up time, Please set your alarm for 5 minutes." And reinforce the heck out of them when they have cleaned up appropriately within the 5 minutes.

Since the dining table + play area will likely be changing over time, I'd put the large piece of art over the sofa, where it has the best light. For the dining + play area, I'd suggest installing a picture rail at ceiling height, then hanging the pictures from it. That will let you move things around as your needs change, without filling your walls with holes. Maybe row of black and white photos, not too small, would look good across that wall. You can buy all sorts of systems and hooks. https://www.decoraid.com/blog/best-picture-rails