I used to just pop down to Fish Hoek on the False Bay coast to spot them with Binoculars when I live in CT but the best location is probably Hermanus where they come in very close to shore at times. I think you can get boat trips these days too. You couldn't when I was there.
Not sure where you're heading on safari as the only places around CT are smaller private places. Should be a decent intro. but not sure you'll see much in the way of biodiversity. The Wine Route can be Ok if you're into that. I used to get wine from Groet Constantia which is a working vineyard in Constantia, off the main road heading to Nordhoek and Cape Point. Very nice place if you don't fancy the Wine Route thing. December is very windy around CT and can be rainy too BTW. It's a fantastic location and there is a lot to do. Cape Point and the National Park, Penguins at Boulers Beach, V&A Waterfront, Muizenberg for lunch and 'antique stuff', fantastic French Restaurant in Simons Town (there is only one!!) walking around the city centre. Yup, I loved living there. You will need a car to make the best use of time.
You are going a bit OTT with two bodies and the 70-200mm IS IMO, but up to you. I'd leave them at home and take a wide angle instead. Remember crime is high in SA, so take care and try not to stand out too much.
We have a Southern Africa safari thread here, which is planning for Namibia and Botswana August 2007. There may be some general info there that is useful and there have been a number of safari threads with good info here if you do a search.
