Does anyone have a sense of how the crowds are in May? To determine whether it is essential to pre-purchase the tickets...
I have bought the tickets in advance for June and October and was so glad I did as there were very long lines. Hopefully, someone can tell you more about May.
We've been there in May: definitely pre-purchase tickets as both were VERY busy.
(We used a pass which is no longer very useful for tourists.)
It is recommended even in May. The lines can be long anytime.
So if u cAn commit to a day, book it.
Such a waste of your touring time the only thing worse would be standing in xtra long lines in the rain,or scorching heat.