Ok, I see a couple of things wrong with the firewall rules, so lets get started.
1.) You have no mangle rule that is marking for connections from what I can see. Without that rule your mark-route rules will never fire since they are looking for a connection with a mark.
/ip firewall mangle
add action=mark-connection chain=prerouting comment="" connection-state=new disabled=no new-connection-mark=wlan1_conn passthrough=yes per-connection-classifier=both-addresses:2/0
add action=mark-connection chain=prerouting comment="" connection-state=new disabled=no new-connection-mark=wlan2_conn passthrough=yes per-connection-classifier=both-addresses:2/1
2.) You have your mangle route rules on the output chain. This will not work as the output chain is only ever used for traffic that originated from the router itself. Prerouting or Forward is what you probably want. Look at the packet flow diagram and see what one fits your needs best.
http://wiki.mikrotik.com/wiki/Packet_Flow#Diagram
input= traffic specifically for the router
output= traffic generated by the router
forward= traffic going over the router (i.e. from clients)
prerouting= traffic before any routing has been done on it
postrouting= traffic after routing decisions have happened.
3.) Not really a problem at this point, but your mangle rule is too general. Either make two of them and specify an out interface, or add in the src-address as your LAN. Without that to narrow it down it will masquerade everything and could have some side effects that you don't want.
This should get you up and running at least and then you can move on from there. Also keep in mind that order of rules is very very important. If something is in the wrong order a rule may match something you don't want it to and once again have interesting side effects.