Sat here saying 'yes' to so many of the simple pleasures already mentioned.
For me:
DH unexpectedly getting some time off work (not due to illness) and being able to spontaneously go for out for a couple of hours for lunch.
In fact any impromptu trip.
Getting something nice in the post - a proper letter, card, postcard, parcel from Amazon etc.
Sitting in the window seat watching the tractor in the field opposite the house.
Watching birds on the bird-feeder when I'm doing the dishes and listening to the radio.
Dancing to silly songs on youtube with the children.
Having a tidy house - if only for half an hour!
Having enough time to have an interruption free bath and manage to do all the things like defuzzing, plucking eyebrows etc. Then slathering on cocoa butter. Climbing into a lovely bed with clean bed sheets too obviously. Bliss.
DH going out to buy something essential from the shop that we need and coming back with a little treat for me - a chicken tikka roll or a Sloppy Giuseppe pizza or Kinder Bueno :P
Putting my twin toddlers in the car and taking them for a drive until they fall asleep then finding somewhere nice to stop - either in the shade of the trees by the river or the viewing spot on top of the hill or just by the cricket field near my children's school and sitting, listening to the radio or an audio book and having a coffee in a thermos mug!
Reading - anywhere as long as I know I won't be interrupted :) I love going to cafes alone too but never get any reading done as I'm too nosey and people watch.
Waking up knowing the babies slept through!