PPR would be tax free.
Investment properties - CGT in Ireland as per usual (if one sold pre year end and one sold post year end, you would actually get the 1270 euro tax free gain per annum for both, this ,may actually double for a couple joint owning the properties, hardly likely to be a consideration, but you never know)
Other Tax implications - Small refund may be due again depending on when you leave, if you are a PAYE worker.
You are ordinarily tax resident in Ireland, I would imagine you are also domiciled in Ireland, thus I do not know of any possible taxes that could affect you in the states. I am no expert on this however and would be very interested to hear what anyone else has to say on this.