My dd (4) requires a high level of interaction for play. She will not play alone at all, not like real imaginative play, so we usually do that together for about 2 hours each day. What works for us, is getting our bodies moving first (we put on music and she jumps on the bed and I on the floor) and then she'll usually come up with a play idea or I will and we go from there. It helps that we read a lot, tell a lot of stories, and really encourage imagination (like we'll pretend we're a family of polar bears putting on our polar bear fur when putting on winter coats, etc.). I'm not trying to imply that you don't do those things but rather these are things I have actively worked to cultivate to a large degree in our lives. Lately, she's been really big into using our sofa cushions and play silks for making caves, castles, etc. Sometime I'll start with a prompt, "Mrs. Squirrel is looking hungry today. I wonder if some forest fairy will help find her some food," and sometimes dd comes up with her own prompts. Today we went to a park for 4 hours and we were all spiders with web homes, etc. I've generally found that the important things are to: 1) start with movement--dancing, stretching, bouncing, whatever, to get out her uncontrolled wiggles, 2) suggest a prompt if dd doesn't seem to be coming up with one but keep it basic, 3) have a good practice of acting out stories from books in general, 4) have a good practice of being very imaginative as a family (do "take a turn" stories at dinner where everyone tells part of a story, do family pretend play together, make the world come alive by talking about fire fairies for candlelight, Father Wind kissing your face, etc.). My dd is very much like a mini-adult/engineer, who likes to climb and jump. Imaginative play does not come easily to her at times so it's something I have worked HARD to cultivate. We have no media for this very reason, and we've studied a lot of Waldorf techniques.
As for toys, sometimes she plays with them in our play, sometimes not, and it really varies by week as to which ones she focuses on. The past few weeks have been couch cushions, pipe cleaners (great for weaving tapestries, according to dd) play silks, stuffed animals, and "ingredients" from her play kitchen (like pumpkin seeds, dry beans, etc.). I generally just go for open-ended things and so far dd's imagination is fluid enough that she will pretend that doorknobs are fishing rods, etc., so that approach I think is working well.
And sometimes, like this past week, she isn't big into "play" but more into drawing, writing stories, and jumping back and forth from our bench to our rocking chair. And that's okay too . . . but I do try and at least help her frame it imaginatively, like being bunnies and such. I probably over do it, though--my dh says I take play way too seriously, LOL!