Hey,
I am currently staying in Diani Beach.
Foil: you will have to bring your own equipment.
For Foil it is good to have a look at tides at this page:
http://wisuki.com/tide/45/diani-beach
In the lowest tide it will be risky to ride here. I would suggest to make a gap 1/2 hour before/ after the lowest moment (of course the water level depends also on the moon period- if you will come in the new or full moon you will find bigger differences).
Wind conditions:
Better to come at the last days of august. Oficially in September starts the rainy season, you will find less people and most probably less wind, but every year is a bit different up here.
Nightlife:
At Diani beach you will find lot's of resorts, hotels, few restaurants and pubs for evening hang outs. I am staying at Kitemotion school at Bidi Badu Resort. We do hang out all togather
beers, movies, pubs.
Difference:
Watamu is a small villiage, where are just few hotels. So if you are looking for a kitespot with kite community attached – in my opinion better choice will be to stay at Diani- beach.
Place we stay:
https://kitemotion.pl/en/
If you need any more updates just write to me on facebook:
https://www.facebook.com/maria.sznajder.7
Windy regards:
Maria