David J.
Yelp
Kensington Gardens is one of my favourite spots in West London. It's more intimate than Hyde Park, with more planting and trees, and it includes the complex of Kensington Palace.
Kensington Gardens is the more developed bit of the gardens to the west of the road (West Carriage Drive) that runs north-south through the park and across the Serpentine: that means that it includes Kensington Palace, the Albert Memorial, the Round Pond and Serpentine gallery, but not the Diana Memorial Fountain.
The wooded area is more thickly planted with trees than Hyde Park, but it also has lovely areas of lawn, particularly around the 'Round Pond' (which is actually more oval). The pond is a great place to feed the ducks, and safe as the water on the edges is fairly shallow. The area around is popular for sunbathing, picnics and kite flying.
Like Fuzzworks, the bit I like the most is the Sunken Garden, which is technically part of Kensington Palace but is free for the public to look at. The Sunken Garden was created in 1909 and modelled on the Tudor Garden in Hampton Court. It is beautifully maintained, with ponds and exquisite borders. It's also a little haven for wildlife. Because the tourists feed them, the birds and squirrels have become phenomenally tame, so it's a great place to get a photo of your kids feeding squirrels (mind - they do occasionally bite, so it's not actually that good an idea for little kids).
The main paths are now quite busy highways for cyclists, but there are paths also reserved for pedestrians only. There are toilets at both Black Lion Gate (near Queensway), Palace Gate (on Kensington Road) and Mount Gate on West Carriage Drive.
At the north end is the Diana, princess of Wales Memorial Playground, a lovely small park with all sorts of things to let children's imagination run riot, like sculptures, teepees, a sensory garden, and the centrepiece - a large pirate ship set in a sea of sand. It has more restricted hours than the rest of the gardens. For adults, there's always the Serpentine Gallery, which runs regular exhibitions of art and sculpture, and occasionally concerts, and is small enough to pop in as you are walking past.
The park has several cafes, which are nice enough, but a bit pricey. The Orangery is very classy, as well as historic: it was added by Queen Anne at the beginning of the 18th century.
Strongly recommended on a hot, sunny day.