I am a Canadian Citizen and have US Permanent Residence through marriage to my US Citizen husband. We are early-thirties, employed in professional careers and own a home in the US. We would like to move to Canada at some point in our lives, likely in 20-35 years (i.e. closer to retirement). I'm somewhat familiar with the Canadian immigration process and am not asking about how we move/immigrate.

I would like advice on retirement investments. We currently have 401k and Roth IRA accounts through our employers. Should we open an RRSP or other Canadian investment? If so, how are contributions taxed in the US? How will we get money from our US investments, and how will we be taxed, after we've moved to Canada?