We have a Cisco ASA 5520 firewall with several interfaces configured for our internal networks, with the same Security-Level = 100 set for all, configured enable traffic between two or more internal interface - still not working.
We have ASA version 9.0(3)
Not sure what's stopping this traffic or what's required to allow all internal networks to communicate together.
If you want to use the ASA to control traffic between all the networks then you should not really configure any routing on the 3750. You should simply configure the amount of Vlans you need on the 3750.
At the moment it seems to me that you are using separate physical interface on the ASA for each of the Vlans ( I presume each ASA interface is connected to an Access port on the 3750 belonging to the specific Vlan). Typically though you would configure a Trunk interface between the ASA and 3750 so you dont have to spend all the physical interfaces on the ASA. You dont necesarily have to use only 1 Trunk interface. You can separate the Vlans to several Trunk interfaces. Then again you could also configure a Port-Channel between the 3750 and Trunk the Vlans to the ASA through that.
At this point I would imagine the simples way for you to go that doesnt require that many changes would be to configure every single host to use the ASA interface IP address (for the Vlan in question) as their gateway. You can also remove the IP address from most of the Vlan interfaces. If you need one for Management purposes then I guess you could leave the Vlan172 with an IP address so you can connect to the 3750 remotely if needed.
If you want to use DHCP then you can either use the ASA as DHCP server for each of the interfaces or you can setup some DHCP server on some Vlan and configure the ASA with DHCP Relay on the interfaces so they relay the DHCP traffic to a server behind another ASA interface.