"While I was in spain"
Should I be using estar or ser? This was only a temporary holiday so I'm assuming preterite since it had a clear start and end. Could be imperfect though, I suppose.
Estaba en España?
I'm assuming if I was describing skin colour, it would be "era blanco" as this is more permanent.
To bypass all of this I could just say: "Durante mis vacaciones en España"
2 Answers
You are describing a place, so you need to use estar. So you can say:
Cuando estaba en España
Mientras estaba en España.
One trick I teach my students to remember when trying to decide to use estar or ser is to substitute the verb "to be" for "to find oneself"... If that makes sense in English, then you should use estar.
In your example, if you say: "While I found myself in Spain" then you can use estar without a problem.
Literally, it would be "Mientras estaba en España". But "Durante mis vacaciones en España" is also great and conveys the same message, though you are adding that you were on vacations, something that in your first sentence "While I was in Spain" the word "vacation" is missing.