A LOT of tallent in that garage NIck... goes for you too! I'm very impressed! Not perfect, true, but very, very good. If you want perfection I think you need to multitrack, but for a 2chan master it is quite good.
I listened to all 3, and my favorite was "Tower City"... the vox and the harmonies are just beautiful. I assume you want opinions so I will give you mine. Please remember I am no authority, but just another untrained ear like yourself, and these are just my opinions.
In the cowgirl song I think you need to take some of the "shril" out of the violins. Play with your eq/ mic settings. To my ears, the fiddles should be a little warmer. Good job however, of bringing it up for the solo part... that was a very smooth transition. I would have liked to have heard them a little more in the rest of the mix though.
On the bluegrass song, the vocals wern't quite where they need to be. They should be more upfront in the mix and the banjo should be back a bit. His part is less melodic, and you want to hide him a little in that one. It sorta seemed like he was stumbling a bit. The guitars should be more upfront.
As for tower city, the vox really grabbed me so everything else was OK! The only thing I really noticed on that one was that the lower frequencies of the guitar(s) seemed to overlap the bass and bleed. Not mic to mic I don't think, but just a certain frequency overlapping and being brought out too much. I'm guessing if you brought down the bass eq on the guitar(s) you would loose this. A 1 or 2 db change can make a big difference... just a dab will do ya! Use your ears. It might have also come from the vocalists breath as she/they were singing. That is what a "pop filter" will help with if I'm not mistaken.
Over all. I would try to get the sound of that sweet upright a little more defined... tweak the eq but try to still keep a natural, fat sound. The soundstage isn't overly well defined. I would like to hear it with both guitars stereo mic'd, but alternately pan one left and one right. You don't have to go hard left/right, but maybe a little more than they are now. They blend together almost too well for my ears. The image as a wholeseemed to be a little heavier on the left. Don't trust your meters 100% in that regard, because different frequencies can be heard at different levels but as a whole they get reported to the meter as something altogether different. Use your ears. I would tinker with the knobs a bit to widen the soundstage some. Put the bass in the middle though. You may also try to bring up the presence on the guitars a bit. In bluegrass music there are not drums, so the strings have to be more percussive. That is mostly the players, but if they are playing that way, you should try to bring it out some.
I certainly feel for you on the whole monitoring thing... try it in a loud club!!! Also, when you listen to this stuff over and over and over your brain starts to turn to mush, so give yourself a break between "sessions" when doing your post work. It's like when doing the "pepsie challange" they always give you a cracker between the cup of pepsi and the cup of coke... clense your pallet with a good pro studio recording through your phones between post work sessions, or even between songs as you are laying down the tracks with the band. I think a baseline is a good way to keep your head and ears straight.
Great job nick... big +T (in 12 I think!)
Matt