(I know you probably know this already, but just in case
For the domains that you don't plan to develop, I honestly can't see that you would get much benefit from owning those names, other than possibly preventing competitors from registering the names. If you 301 redirect the domains, they will have no content, and so will not be indexed by the search engines in most cases. No one will link to them, so even if they do get indexed, they won't show up for any searches, and without links the search engines won't even have a way to find them. The only way you would get any traffic from these domains is if someone manually types in the domain name. And honestly, how many times have you guessed a domain name and typed it in your browser?