When I can afford it (about 75% of the time), I have gone on Solar Return trips for over 20 years. I pick a place based on where the chart would be favorable and do-able. Once it took me two weeks to find a location because there were no places with hotels anywhere along the 45 degree angle line of the chart I wanted. I live in the USA and have almost always found a location in the USA or Canada. Only once did it land in Estonia and I could not afford it that year.
The way I believe it works is that you go to the SR favorable location for 24 hours starting from the time of your actual SR. That sets up your SR for the year. IF you lived there for the entire year, then that SR chart would be 100% accurate for the year. However, since you normally return to the location where you're living, I found that it ends to be about 30% accurate for the SR trip location chart. When you have a bad or unwanted results SR home location chart (such as 5 planets in your 4th and you really don't want to move), it helps somewhat. You may or may not ending up having to move. But 30% better is better than 100% bad/unfavorable. I also suggest you go by yourself, as this is like jello and you don't want other people's "stuff" in your jello/affecting your year's events.
It's very interesting to see what kinds of charts you can get. I often try for a grand trine using the Ascendant.
That's what I have found.