This is an interesting question, let's examine it some more.
Townhomes are primarily a first step in home ownership. Ownership ins townhomes are usually condo or pud type ownership. puds are better, as you'll actually own the land as well.
There are also two types of townhomes in this area. One aimed at the entry level market and there are townhomes aim at attracting buyers that can afford a single family home, but choose not to.
Erica has a point, when she says that a townhouse, if not beautifully updated will not be worth as much, as a nice home on a nice lot. Erica also fails to point out that the same is true for a single family home of the same age.
Bottomline, if a SFH is not "beautifully update" it will not be worth as much also. The townhouse, if the HOA is worth anything, will make sure that the exterior of the townhouse is in excellent condition. The same can not be said for a SFH.
Take this test, drive down a random street in the 95008 zipcode, or the nearby Cambrian Park area. You'll see tons of 30-50 year old SFH, that are not the most maintained properties. Drive down a nice community controlled by a HOA. Vizcaya (the community mentioned), or somewhere similar. You'll notice that all the units - from the outside - look excellent. The landscaping is well maintained, etc...
This is the one benefit to a HOA controlled community (this could mean townhouse, condo, or SFH.. an increasing number of newer developments are under the control of a HOA... it's a trend... :-) )
The 2650sqft townhouse in vizcaya, with the 5000sqft lot sounds like a winner. It rivals a SFH in everryway, besides the type of ownership. It is an end unit, and the lot size is comparable to most SFH in the area. (The unit seems to have been sold... I did a quick check on mls, and the only "former model home" in vizcaya closed in dec).
Botttomline, I think SFH are the great value, and you can certainly will have the flexiblity to make improvements on the lot within city guidlines. But don't overlook a luxurary townhome. Luxuary townhomes were build for potential SFH shoppers, and manytimes these ttype of townhomes actually command a premium.
Don't stay away from a townhouse just because it is a townhouse. Home renovation (espically the kind of renovation and remodeling needed to bring a 1950s - post WWII house - to "luxuary" standards is not for the faint of heart......) is not for everyone.