By the time of this post, I'm currently Marathon-ing the show by location up to the end of Season 5. So before first watching today's newest Season 6 episode, "Newbie Dash", I would watch the episodes that take place up in the clouds of Cloudsdale in chronological order. (I already did the Season 4 episodes that took place at Rainbow Falls: "Rainbow Falls" and "Trade Ya" and I already did the episodes taking place in Canterlot, including "Rarity Investigates" so I would avoid them.)

Originally, I was planning to watch the events of Dash's first sonic rainboom, viewing "Cutie Re-Mark" and "Cutie Mark Chronicles" on multiple screens. Then, I would continue with Season 1's "Sonic Rainboom" (the first appearance of Cloudsdale) , then Season 3's "Wonderbolts Academy" (I consider the academy to be part of the Cloudsdale location) then Season 5's "Tanks for the Memories" (because of Rainbow going to the Weather Factory to stop winter).

But after S1's "Sonic Rainboom", I thought I should include Season 2's "Hurricane Fluttershy" because while we don't go to Cloudsdale, this episode does show how the water cycle works in Equestria, plus the scene where Rainbow had to restrain her tough attitude to ask Fluttershy to join the tornado crew would make beautiful contrast in the upcoming episode, "Tanks for the Memories", where Fluttershy would firmly, and a little tough, have to tell Rainbow Dash that her "winter is going to be petless". Then, I decided to add Season 4's "Testing, Testing, 1, 2, 3" because despite the implication that Rainbow was up in Cloudsdale (or wherever she took the test), Rainbow had to learn the history of the Wonderbolts (and it gave me an excuse to see the episode I consider to be the most personal and relate-able episode even to this day).

So in the end, I ended up watching an episode from each season. (Time-Travel episode and brief flashbacks notwithstanding):
Season 1: Sonic Rainboom
Season 2: Hurricane Fluttershy
Season 3: Wonderbolts Academy
Season 4: Testing, Testing, 1, 2, 3.
Season 5: Tanks for the Memories
ending with....
Season 6: Newbie Dash.

What a day it was today!