If you're 6'6, the 25" frames you've been looking at could well be too small for you.

25" = ~63.5cm. You might be a candidate for a 26" (~66cm) or even a 27" (~69cm) frame.

There are some classic manufacturers that made frames larger than 25". Schwinn in particular made 26" and 27" frames if memory serves.

I would strongly recommend not purchasing any bike at a distance, meaning you've got to test ride first. I know the bay area is an expensive market, but if you could expand your search to nearby metropolitan areas, say Sacramento, you're within a drive of a test ride.

If you buy a bike that doesn't fit you well, you tend not to ride it unless you absolutely have to, as your body instinctively understands that it becomes less comfortable the longer you ride. If you're lucky enough to have more than one bike, you tend to reach for the bike that fits you best rather than the bike that is best suited for whatever type of riding you're doing. So start with a bike that fits you first.