A nice outfit of clothes - not nice for parties - nice jeans and top set maybe that they'd wear at weekends for being nicely dressed but not uncomfortable.
PJs, dressing gowns, wellies, rain gear etc.
Sports equipment and/or clothes, or good gear bags. (A bicycle??)
Books - fiction and/or reference (nice atlas or dictionary) or other non fiction (travel, recipes, science etc).
Globe
Science stuff - telescope, microscope, DIY kits
Real equipment for baking, tools for DIY etc - including any necessary safety or "anti-mess" equipment (goggles, helmets, gloves, aprons etc).
Craft things - either things that get used up like paint, glue, papers, stickers, foam sheets etc - or equipment - easel, scissors, brushes, ....
Nice bedroom sets - sheets and duvet covers - in their favourite characters or colours. Their own swimming towels.
I've probably repeated loads of ideas - just thinking off the top of my head.
Have you asked the DCs if there is anything they want/need/would really love in their dreams?