I totally agree that as far as investors are concerned Silicon Valley has more expertise concentration. On the other hand, Silion Valley also has more number of startups seeking funding!
In a web startup where geographic locations are not a huge factor for the product development itself, it is harder to justify high cost of living with other benefits hotspots in US like Seattle and Silicon Valley provide.
My current startup is in Seattle and we are bootstrapping right now. We are strongly considering about moving to another country. Startups are about people, as we all know. Seattle definitely had better resources to get support, advice, and seek funding. However, we had to let it all go over the vast cost of living difference between India and US.