Generally rachmaniff piano pieces are inapproriate for less tham early advanced levels. Thas why they are hard to categorize as anything other than advanced
Texture, voicing, polyphony, inner voice melody and counter melody....all can pose sigificant challenge to les experienced pianists.
i canot really give an "easier" of the lot sugg since i hobesty dont think we ca stick his pieces in that tier
there are pieces w tha sound tha can grant access to a similar lovelyness though
ue this score is rare tooke a couple years to fund but its out there, its a short version(the long ver is better but harder) of Ruchardson's Fantasia and love its sound. Its not that hard, not easy but way less challenging tha the rachmaninoff pieces ive looked at