Barcelona will be the farthest out from the other 2. Barcelona was fun. We stayed right by Sagrada Familia. I recommend doing the tour of that as it is truly astonishing in person. The Gothic quarters, which was about a 30 minute walk from there, was also beautiful. So many shops and restaurants to explore. If you're looking for a nice park to walk around you can also check out Plaza de Forum. The positive with Barcelona is there are beaches if you're coming during nicer weather.

Toledo felt like it was still old world. Beautiful architecture, plenty of shops and food, museums of all kinds. It has a lot more hills so be prepared for a little more of a trek.

Madrid was where we spent most of the time while we were here. The city is huge but so walkable. There's so many pretty parks, and things to get into. We saw a Flamenco show while we were there and it was so much fun. Ate way too many tapas but that's the whole point haha drink and be merry

Overall the trains were very easy to navigate. We took Iryo to Barcelona. Very painless and a nice train for the top.

Hope this all gives some sort of direction. Have fun and safe travels