What is it about newness that excites?
Having something major that entices excitement. Whether that be a new coaster, immersive dark ride or unique water ride, it can be an addition which offers something different in that park that hasn't been seen before.
There are of course times when I'll be more excited for some rides more than others. For example, my excitement for something like a GCI woodie or B&M than something like a gerst. However if the park went all out on theming, landscaping etc. Interest would spike. My interest in flats is generally low unless again they're well themed or unique.
Things along the lines of CBeebies land and Thomas Land have no interest to me.
How important is story to a ride?
Depending on the ride, it can be highly important. At a park like Disney or Universal, it should be a given. The same can be said for dark rides where unless it's a coaster, using one is paramount. Of course fairs and amusement park rides don't necessarily need a story due to the nature of the parks.
Are there rides that give you the same enjoyment each time?
Select number of rides achieve this, including Nemesis, Megafobia, Joris, POTC,TOT and BTM.
Some rides even get better upon re-riding like Baron 1898, Swarm, Air and Valhalla actually improve.
Although in some cases enjoyment can drop. This has happened a few times on rides like The Smiler & The Big One.