My dd's also 7 months...
I like to put different tubs, pots pans etc on floor and show dd how to hit them with a wooden spoon to make a racket. She loves doing this and it keeps her busy for a while.
She likes to be in the sling on my back while I potter...mow the lawn, put out washing, anything where you are moving around a lot. She seems so content there for ages and ages.
I try to get down on her level while she is on the floor - crawl around with her or 'join in' with what she is doing every so often. My dd finds this hilarious. I lie on my back on the floor and she spends time prodding at my face like it's a strange new toy.
I feel weird about leaving dd to play on the floor too, but she seems very happy to do so, and I figure that it's good for her to have some time where she is exploring and observing things for herself rather than being constantly entertained.
I completely empathise, it can be draining thinking of things to keep them happy all day!