I mostly used EQs, some Compressors and a little reverb. Guitars and piano are doubled and panned, also panned the dobro and fiddle a bit.
So far, I like the mix, but I'm not sure if I missed something or didn't use the EQs properly.
thanks for sharing your mix! Nice song that you picked there :-) My first impression from a quick listen on desktop speakers is that the center is quite crowded with upper mid frequencies. What I'd try next is to not just "pan a bit", but pan much more radical!
Then I'm curious why and how exactly you doubled guitars and piano. What did you hope to achieve? How did you treat the doubled track differently from the original, apart from panning? Unless you already did that (it does not seem so), I'd suggest you try to equalize the sibling tracks slightly differently, and/or delay one of them by, let's say, 20 and then 40 ms and hear what happens with the different settings.
What I find great about this site is the opportunity to easily compare different mixes of the same song and then discover about what one can make decisions, and how one can make them. You may want to compare your mix to others, and hear what you like about each of them. On the other hand, you may prefer to develop your own idea of a song before you listen to other people's treatment of it.
About the panning, I didn't really want to pan the dobro and fiddle too much, since they are more important. Then electric guitar, piano and acoustic guitar are more panned from 40-80%.
Concerning the doubled tracks, I just used the Haas trick to widen the mono-track-instruments and delayed the double track by 10ms. Apart from panning, I didn't treat the tracks differently and also I'm not sure how I would do this properly to keep the balance.
Moreover the piano might be a problem and a little hard to notice.
A nice earthy quality to this mix, which suits the material in a way. You've kept the vocals nice and clear as well, which is an important decision well-made. By the same token, though, I'd have liked to hear the violin and guitar solos coming out a bit more clearly during their featured moments.
In terms of improving on what you've got already, the big thing it seems like you're missing is clarity -- that sense you can hear inside the details of all the sounds, and that each instrument/voice can be seen through clear glass. At the moment everything feels rather muffled and as if the instruments are getting in the way of each other. I think this is partly on account of the reverb treatment you've used, which seems rather uncontrolled at the low end and in the low midrange, as well a rather coloured tonally. It just sounds like the wrong reverb algorithm for the job. I'd look for something natural-sounding to bind everything together, but leave it nice an short so that it's not cluttering. Get your EQ busy in the effect return to cut away any build-up of muddy-sounding frequencies, so that your instruments can sound in the low-mid region more clearly.
However, it's not just the effect responsible, I don't think. It's almost certainly a question of frequency-masking too. So try to do some cutting with EQ to see of you can weed out unnecessary frequency information on any tracks that's obscuring important frequency regions on other parts. Hope that makes sense!
Otherwise, it sounds to me like your balancing instincts are in the right place, so it shouldn't take too much work to make a big improvement I imagine.
I thought it might be nice to give so some quick feedback to your first contribution here, but, while being indeed quick, I did not notice that I was listening on a broken speakers setup, which all but collapsed the stereo spread . Listening on monitors, I hear that you already are where I meant to send you. I may however add that in order to play Haas tricks, you don't need to double tracks. Voxengo's Sound Delay, configured properly, lets you do that on one stereo track. It's a bit clumsy to use, but free... and there are probably other plugins that are the latter without being the former. But since you already doubled the voices, you may as well try to eq both sides differently. I like the effect of it, and I reckon you will like it too . The good news about my mistake is: your mix seems to fold to mono nicely without losing much.
Listening on proper gear, I really like your mix. Mike already mentioned your "balancing instincts". But then... there still is something to my original impression "that the center is quite crowded with upper mid frequencies". Mike points to reverb and frequency masking. I wouldn't be sure about the reverb, but rely blindly on Mike's ears (pun intended). Yet I still believe there is indeed some contention between the voices around 3 kHz or so, independently of any reverb side effects. I would try to eq everything a little leaner in that area (the "weeding out" Mike talks about). An indicator is to me that by cutting 3 dB at 3 kHz, I got an overall frequency balance that sounded slightly better to me.
What bugs me a bit at this point is the drums. I find them a bit sloppy all by themselves, but in your mix, they seem even sloppier. That may indeed be a reverb issue. I wonder what you did to the drums...
I actually didn't use a lot of reverb, just so that it's barely there. Maybe the choice of reverb or settings wasn't right.
When it comes to clarity, this has been always an issue for me and I'm not really sure what frequencies to cut and what to boost, so there should be much to improve on my EQing.
@ThePhonk:
I'm glad the mix sounds better for you now. For the stereo widening, I thought about using a plugin, but I just went for the doubleing.
Also, I didn't really do much to the drums. In order to make them punchier, I added light EQ and Compressor for snare and kick and fiddled a bit with the other track's EQs. The room track might be a little bit too loud and treated wrong.
I will try to work on the mix with your suggestions in mind.
. Listening on monitors, I hear that you already are where I meant to send you. I may however add that in order to play Haas tricks, you don't need to double tracks. Voxengo's Sound Delay, configured properly, lets you do that on one stereo track. It's a bit clumsy to use, but free... and there are probably other plugins that are the latter without being the former. But since you already doubled the voices, you may as well try to eq both sides differently. I like the effect of it, and I reckon you will like it too 
. The good news about my mistake is: your mix seems to fold to mono nicely without losing much.