What others (above) have already suggested.
In addition, panning i.e. guitar could be a little further away from the piano. Another consideration is the actual instrumental-arrangements, sometimes too much play can overwhelm other key instruments, and no matter how well its mixed -- getting clarity, separation from all instruments will be a challenge. Unusually subtle (careful) filter-cuts in areas of the frequency span that are overly pronounced can work wonders. To assist with that - what Bapu suggested, Voxengo's SPAN.
I usually try not to over-use sustain pedal on the piano. And also, what I do is separate the bass (piano) to a separate track -- this allows me greater control in the mix and to give the bottom end more clarity and punch. Works wonders for typical compositions that have bass, drums, guitars (L/R), piano.
From what I've heard so far, your compositions and performances are excellent.
Wish you all the very best!