I am not sure that there is a site that can give you vacancy rates by location and property type with any degree of accuracy (although I have seen reports that agents have collated on their own), because there are variables that influence the vacancy rate, which would not be seen without drilling further down into the data. However, I will tell you that across the valley vacancy rates are in the neighborhood of 10% plus or minus a few percentage points depending on the area. The spread is so small as to be insignificant. Frankly in this extremely strong rental market, the only real determinant of vacancy and how long a property remains vacant is the amount of rent a Landlord determines that they MUST get. If you are even $25 to $50 over market rent, your property will go vacant for an inordinate amount of time. On the other hand, if you are $25 under the market, your property will have multiple rental applications within 48 to 72 hours of hitting Craig's list.
I assume you are worried about your rental property remaining vacant for an extended period of time. That just does not happen in this market, unless as I said, you are trying to get over market rent for your property. I have seen investors hold out for an additional $100 per month on a property and have the property go vacant for 2 months. At $1100 per month, that is a loss of $2200. If you were eventually successful at getting $1200 per month, when the market rent is only $1100 pert month, it would take you 22 months to break even, and there is a greater likelihood that your tenant will move out early, or be a bad tenant, which is the only reason they would pay over market rent in the first place.
Lastly, property values are so low right now in relation to the rents they command, it isn't worth fighting for a few extra dollars of rent per month. You may be entitled to bragging rights for getting the highest rent in the neighborhood, but at what cost in the long run? Cash flows are incredible right now, so dive on in. The investment water is great!
Hope this long explanation helps.
Best of luck, and thanks for reading.