I came across this thread while I was doing search on travel.. This is very interesting topic. I have to say that I have been very fortunate to have 4 citizenships. I have 4 passport that I travel with all the time and fortunately I didn't have to get naturalized for any of them.
I was Born in the USA so I have a US Passport since I am a natural born US Citizen.
My father is a British so I have a British Passport by decent since birth.
My Mother was born in Australia but she was born to a Canadian Father and Australian mother so she acquired both Canadian and Australian Citizenship since birth. So that Makes me a Canadian and Australian Citizen as well since birth..
My parents have lived in England, Australia and Canada and USA over the past 30 years and my mother became a British citizen because she got it through marriage with my father.. My father became a Canadian and an Australian Citizen through marriage as well respectively when they lived in Canada and Australia.. I have lived in all 4 countries along with my other siblings who are also citizens of 4 countries. My Parents had a good plan for us so I am grateful for that.. At the time myself and my siblings were born they were working in USA (TN Visa as Canadian Citizens) and gave birth to us in USA so we are all natural born US citizens and we were Canadian Citizens right away when they took us back to Canada.. For British and Australian they applied for us by registering us as British and Australian Citizens by decent.
I have traveled all over using all 4 passports and I can tell you it feels absolutely amazing being able to go and live and work or own businesses anywhere in USA, Canada, Australia, New Zealand and All over Europe (EEA). I use the passport to enter and leave the country I am going and leaving but I carry all four with me at all times just in case I need to travel to one of the 4 countries (including Europe as I do a lot of business traveling all over)... I only use British passport when I am traveling in Europe as it is the only way to travel and live unlimited amount of time anywhere in UK and Europe without any hassles of obtaining a visa or permit. So I consider myself one of the luckiest people alive and so do my siblings and we are thankful to our parents for all this..
I think having those 4 citizenships is enough lol and I would think these are probably the best 4 citizenships anyone can have and even better without being naturalized as in my and my siblings case...