Hi!
If you are using IPSec tunnels(no gre)...routes are not mandatory...
Let's say that you've got a router at site 1 and a router at site 2. Those site are linked by the internet(ISP). The default route on those 2 router point to the ISP. In that case, you dont need to have a static route to the other network. You'll use static to force trafic to go tru a interface where your crypto-map is applied if it's not already the default behavior.
The Crypto ACL will decide what goes accross the VPN tunnel and the ACL must match(reverse) on each side of the tunnel. Also, make sure you dont NAT the trafic between the two site if you realy dont need to.