Kerry Mills' At a Georgia Camp Meeting is one of the most famous cakewalks that helped bridge ragtime and early popular piano styles. It is distinguished by its infectious, march-like syncopation and bouncy melodic figures.
The primary challenge is maintaining a steady, driving tempo while executing sharp syncopations in both hands.
Comparable difficulty and character — good candidates for what to learn next.
Cake-Walk is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 4.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Cake-Walk lasts about 3 minutes.
Cake-Walk is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include 12 Variations on "Ah vous dirais-je, Maman" by Wolfgang Amadeus Mozart, Alexander's Ragtime Band by Irving Berlin, Waltz in D-flat major, No. 1 by Frédéric Chopin — see the full similar-pieces list on this page.