Our plan is to downscale and keep a home base in the US but to pick a country and rent something for months at a time. Get bored of it, pick next country... We've done 10+ years as expats so know what to expect living outside the US...
As mentioned above, medical insurance is an issue until you get to Medicare age. Outside the US, you can get private insurance for $3k/year while in the US, it's around $3k/month. 2 more years of high school and our kids are off to college and both are looking at University in the EU as they also have EU passports so we'll look at EU destinations for us one I quit working (or O&G tanks again and I get made "redundant"...)
One thing to consider is that it can be difficult to open a bank account in a foreign country if you don't have an employer who assists you. Many foreign banks hate dealing with US citizens because they hate all the reporting they have to do on your accounts back to the US Treasury. (Pro tip: if you do live as an expat and have an account in a foreign country, don't close it when you leave so you can always use it later if needed...)