Suppose a US citizen is married to a foreigner. The foreigner has lived in the US with nonimmigrant G4 status for 18 years. They married four years ago.
The foreign spouse, after retirement, will need to apply for permanent resident status in order to continue living in the US. There appear to be two options, namely, either to apply for adjustment of status while remaining in the US or to leave the US and apply for a spouse visa. The first option requires filing form I-485, which has a $1070 filing fee.
The fees for the visa route seem to add up to considerably less than $1070, but there also seem to be several different fees and it is not clear to me that I've been able to identify them all.
The question is:
What is the difference in total cost between the two routes, and are there significant benefits or risks associated with either route that should be weighed against the costs?