Raised bed for flowers OR turf?

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Have just removed old patio slabs from this area in the picture and removed about 3-5 inches of gravel. There's still gravel and sand underneath. Have put on 100 litres of compost and topsoil as you see.

Should we lay down some fancy unusual turf ?

Or (my preference) a raised bed? Would like to make it a pretty patch and ideally have some flowers but not sure what's shallow enough? Any perennials? Or would it just be annuals?

Any ideas on how to make it pretty?

I posted previously and got excellent suggestions for what to plant but now that I see that it's quite shallow not sure what would work or if those would work with a raised bed

Here is the previous thread Help me plan a new flower bed
www.mumsnet.com/Talk/gardening/2912370-Help-me-plan-a-new-flower-bed

A raised bed would be a good idea if you are keeping the play area, as it will prevent the plants being trodden on.
Annuals are more delicate, so I'd plant a mixture of perennials with a few annuals.
Lowish perennials such as hebe, cranesbill geranium and a few for height such as verbena bonariensis or some tall grasses, would be tough. Then you could put in some annuals as well.

I've got a border with very shallow soil - right now a lot of healthy perennial geraniums, oriental poppies and lupins leafing up, among a sea of self-seeded forget-me-not, with some bellis (I think thats what they're called - fat bright daisies) at the front for seasonal colour. There are also some self-seeded honesty and aquilegia in flower and foxgloves springing up.

Maybe some ideas there?