Need hints & tips about Namibia

Hi Africamers
I am planning a trip to Namibia in Oct/Nov. this year. Have been before, but thats 10 years ago when I lived in Cape Town. Now I am living in England and my trip will start at Windhoek airport. My rough itenary is:(approx. no. of nights in brackets) Etosha (6), Swakopmund (3), Fish River Canyon (3). However, I have +- 18 nights at my disposal. Any suggestions? Will hire a car, any good recomendations are welcome.
Thanks