Smell of polish and fresh laundry in their house. If I dig my nose right into some of the soft furnishings I inherited from them, the smell is just there still. 
Roger et Gallet fern soap
Fresh rolls for breakfast with Alpine butter and forest honey. Pretzels with butter. Sugar puffs (called "Smacks" in Germany) with warm milk in an antique porcelain bowl with fish painted on it. Little porcelain cups with blue violets painted all over them.
My hugely elegant German grandmother doing silent but deadly farts at the meal table. 
Going for lunch in town, stopping by the toy shop or a posh children's clothes shop and being indulged.
Being taken into Dallmayr, a Munich institution a bit like the Fortnums food hall, to look at the lobsters and live fish in tanks.
Being read stories from Richard Scarry books in German whilst sitting on my grandmother's knee.
Playing peekaboo with my grandmother. Her teaching me to embroider, buying me stickers and letting me mess about with rolls of sellotape.
My grandfather pretending to be the big bad wolf round the back of the play house, until we screamed with pleasure. Also him taking us on Alpine hikes with little backpacks and Toblerones, going up mountains for hours and hours, and getting us all dirty.
Being fed a lot of cake.
Being tucked into bed when I had eaten too much cake, and cossetted with chamomile tea.
Very fluffy goosedown duvets.
My grandmother growing sweet peas in the garden.
Playing football with my grandfather in the garden.
Pottering around the garden with a little wheelbarrow, or a bucket, pretending to garden or do washing.
Going down to the basement to see the housekeeper at work in the laundry room, and chatting for hours even though we didn't have a language in common (I didn't speak German as a kid). She's still alive and we visit her regularly, and she does all the things with my kids that she did with me, even though she is about 90 now!
Being taken swimming in lakes.
Sadly my own parents don't do any of these things for my kids - they see them for half a day at Christmas once a year - their choice.