I keep my boat at Sooke Harbour Marina.It is all the way through Sooke out the other side. Wolf is right in that Sunny Shores is a much better ramp at low tides (the Sooke Harbour Marina one is a genuine Pita) but if you plan to keep your boat at the marina and not trailer it, then the ramp shouldn't make a difference. The reason I like Sooke Harbour is it is closer to the mouth of Sooke Basin thus cutting down the amount of time coming in and out of the harbour, especially when it is socked in.(It often is, in the summertime.) I know they still have space left as I went and booked just last weekend. There is a new marina right next to Sooke Harbour Marina that you might try as well, but I can't recall the name. You'll see it when you get there.
Tom