I have planted lots of lillies, doesnt fill bare earth though.
I was prepared this year, done wallflowers and bellis daisy from seed, so nice lot of green there, planted lots of pansy's,sweet william, primula's ,christmas roses, lilly of the valley, trailing pansy's and ivy in hanging baskets, hebe's just planted.
I have lots of delphiniums waiting to go in, but was a bit frightened that the weather may turn so keeping them for the spring.
I think you could still put tulips in, maybe a bit late for daffs, some places are still selling snowdrops 'in the green'.
Maybe, next year, you can start perenials off early for an autumn planting.
I think its best to only grow wallflowers once in the same place though.