S.H.
I've been to Spain and can't wait to go back. If you're going to be using the subway in Madrid, you'll want your stroller to be easy to either grab and carry on the subway or collapse easily. Would you consider a backpack type carrier for your infant? The streets can get crowded in the larger cities and might make handling a stroller difficult. Beware of beggars and gypsies. The pickpockets are very talented and having stroller to contend with might make you an easy target. We never had any problems but there was a group of Japanese tourists whose tour guide had all their passports and money she was carrying stolen from her. The gypsies are infamous throughout Spain, if you need more info on safety feel free to write me back. I found that the less I carried the easier it was to maneuver. The streets themselves weren't too bumpy. Even in Pamplona where there is cobblestone it was not any worse than a brick sidewalk. I didn't travel on any unpaved roads. Everything in Spain is pretty well paved. Only out in the country do you encounter dirt roads, and even those aren't bad. Good luck!