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.

I used Flor carpet tiles in a kids play area in a commercial setting. I ordered extras and could then have the individual tiles washed or replaced as needed. They held up well and the selection is fun. The rug you are looking at is nice too! Here is a link that might be useful: Flor carpet tiles

If you have a flood risk in the basement, I'd say something waterproof like tile or terrazzo. For the playroom area, put down a big cheap area rug (like a section of basic carpet that's not nailed down). Then if it floods again or the kids make a gross mess or spill, you can haul the rug out and get it cleaned, and the floor underneath will be unaffected.

Here is a 3D rendition with several of the suggestions incorporated; for your consideration. Yes the furniture is not exactly like yours but it's the placement that is being presented. The seating area is just as you already have it with a slight adjustment. The world globe is not in the rendering The long bench has been replaced with a cubby with containers in it (dollar store, love it!!) A floor lamp like the one you already have was added Two baskets for toys A storage unit with more containers like one you can find at IKEA; Kallax it believe As you can see the dresser and mirror were moved to the opposite wall to make room for the storage unit.