I do not race Ironman distance, but I can give you a couple of hints. I have raced Vitoria half distance and it is a beautiful race. They hold an Ironman the same day. Mostly flat.

If you like hard climbs, then the KM0 in Madrid is for you. The bike goes over several category 1 Vuelta climbs. Then the race ends in the very heart of Madrid. This race has been bought by Challenge.

I will look into it. Madrid would actually be better since my wife is from a city an hour outside Madrid.

I did Barcelona in 2015. The race is actually starts in Calella. It is flat and fast - following the coast the entire way. I enjoyed the visit there and thought it was a very nice venue. Book your hotel early though, as they seem to fill up quickly..

Well, the locals consider Barcelona being in Catalonia, not Spain ... apart from that, Barcelona is a great race, hotels, food and transport are cheap. Paella is awesome if you go to places frequented by the locals/spaniards/catalans.

If you get emotional about large (LARGE) draft packs, this may not be a race for you.

I think the Challenge Madrid bike course is quite tough on the first 90k but mostly downhill afterwards with a significant net elevation loss.

Other than that there is Ironman Lanzarote (hilly and windy) plus some obscure ones you can find here:

https://k226.com/events/events.aspx

Vitoria - Gasteiz gets great reviews:
http://www.triathlonvitoria.com/