Start with the ones with the bright, cheery lines with the obvious "fun ride" payoff. Hold off on the ones with the darker lines, or the darker rides until he's used to what a ride really IS and what he'll get from it.
While you can nearly see all of the line of PP from the outside, it is perhaps a bit darker than, say, the iasw line (from my memory of my experiences), so maybe hold off on it a bit. Just see how he does and take things slow. And make sure that he's nicely fed, well watered, and well rested before trying anything even a bit worrisome.
How did she do on HM? We're taking our 17 month old in 12 days....
From our experience, having taken DS to
Disneyland for the first time at 17 months old, he didn't mind ANYTHING at that age. Just a year old, no strong opinions on much of anything apart from being held, getting his mama milk, and having his diaper changed (wanted to be clean, hated the process...he was of two minds, there, LOL). Slept on POTC, etc.
When we went back a year later (at about 2.5) his opinions on things had changed DRASTICALLY. I never even got on Disneyland's HM that year, because he flipped out while just in the line (stretching room screamers did not help at all...wish they had a kid-friendly stretching room!) and we had to take the "chicken" exit (which, at DLR, was actually darker and spookier than the line, and we were all alone in long corridors...augh).
He continued to change and be different about rides on almost every trip after. He'd love a ride he hated, he'd hate a ride (or even a line) he'd loved. Back and forth. Crazy fellow.
At 17 months, though, he was Zen about everything. It was all about being close to his family, not about knowing if there was such a thing as being *scared* or not.