Trying to figure out how to use the different mix settings in the OCTA to monitor direct, but I think I'm still feeding SONAR's main outs to it. 

I'm not sure what your asking but.
 
You can set your master, sub master outputs to other mixes in the OC by setting the output to 3/4. You can adjust the OC's setting in it's mixer. You can create 4 monitor mixes as well.

Octa Capture is working very well for me, both solo and interfaced with my VS 100.  AS Guitarpima stated, there are 4 monitor mixes available as well as 4 groups of outs (1,2 - 3,4 etc that can be routed in any combination to your main outs. 
 
Could you give us more info on what you are trying to do?  Thanks.
Clint H.

Well, I'm trying to record into the interface on a channel (7), into SONAR but monitor the direct input without going through SONAR...but also hearing SONAR's main outs (obviously, as we're recording vocals and need to hear the music). I figured this was the best way to get some low latency. Also trying to figure out how to get compression (that's easy) and the reverb working on the OCTA for a monitor mix for the talent. I'm coming direct out of ch3 on the OCTA, and trying to figure out how to setup a mix for that. Looks like the mixes are hardwired to specific outs on the OCTA, which is fine. Still, only have the reverb settings on Mix A.

On the right side of the OC mixer are the direct outputs. You can route Sonar to any of those. There are two sets of double faders also. The one on the right is the mains. The other one is for monitor mixes. I always leave the mains at 0db. The monitor mix volume may vary.
 
On the left side is the monitor  mix. You monitor what your recording there. Make sure channel 7 is not muted and it's volume is up.
 
You may have set the incorrect outputs within Sonar. Make sure your master bus is set to outputs 1/2.

And what the deal with the reverb? I just do not get how that is routed. 
 
And phones are distinct from all of the monitor mixes? It seems like they only monitor main outs?
 

On the left, monitor inputs, there are reverb send knobs. On the right there is a reverb return knob. You can press the reverb button, on the right, and select from a few reverb types and set pre-delay and time settings.
 
Yes, the phones are tied to the main outs.
 
May I suggest reading the manual?

haha, I know! I've got it up on the DAW computer but I'm at my work desk. P.41 starts the routing info, I just haven't gotten there yet. :-)
 
Thanks for being the Cliff's Notes though!