Have been to both Spain and Italy. Stick with Italy for now since you've done all this research. Next trip can be Spain.
I've been to Spain once... to Italy more times than I can remember. If anyone asked me where I'd like to go now.... it would
be Italy. On the other hand.... you definitely should visit Spain (and Portugal !!) at some point.

I've never climbed that tower and have no interest in doing so.

Havent queued up for the Eiffel Tower either.

But loved going up the tower in San Gmignano, the Torre Mangia in Siena and the Campanile in Florence.

Great views from these towers.

I've spent three nights in Bologna and liked it very much, but if it were me on this trip I'd cut it and add those nights to Rome and Venice. There's just so much to see in each city, including more off-the-beaten-path museums, neighborhoods, etc., that tend to be a bit more enjoyable than the major sights. So it's nice to have time for both--can make for a better experience. Anyway, just my opinion and I'm sure many disagree. Naples seems to be a love-it-or-hate-it place, at least on this board. I'm firmly in the love camp.

I saw your other thread about Italy or Spain first. Not sure anyone can answer that one for you. Just go to the place that is calling to you most first.

FYI: The OP has begun a new thread:
Spain or Italy for first-timers?

I've climbed the Leaning Tower thrice and always got a thrill out of it - a feeling only can get from climbing a tall really tilting tower!

PalenQ... I don't have a problem with heights.., but I started up the Pisa tower and had to turn back.... a very strange sensation.
My husband had no problems and made it to the top. I've often wondered what bothered me... ear problem? neck problem.... lots of arthritis...
'Tis a mystery.

Wow - yes a mystery - it's not for everyone. Was it vertigo?