I visited Picton from Wellington for 5 nights with my husband and 6 month old baby. It’s a lovely warm house close to Pictons Main Street (and the supermarket), the bedrooms are on the small side (but we could comfortably fit a travel cot in the double room), the living room is spacious, and the couches are so so comfy.
We bought our car over so we could explore the area a bit, but the location is so handy you could easily pop over from Wellington without a car and see lots of Marlborough.
We spent heaps of time reading at the Airbnb and doing short day trips with baby and it was so quiet and comfortable.