People have mentioned a couple specific ones but I think in general the major encounter locations and dungeons of Lost Mines need to be highlighted (Cragmaw Cave, Cragmaw Castle, the Redbrand Hideout, the Phandelver Mine, whatever that ruined town with the Dragon was called). They all were of reasonable digestible sizes, but still had interesting things going on, usually (or, depending on how you played it, always) had some sort of factional dispute players could theoretically exploit, with minor tweaks they had sensible enough ecology, and, a rare thing indeed in dungeons, all of them made more or less made enough sense to exist as locations that it didn't bother me (even if I feel like everyone in town would have figured out the Redbrand hideout). Both Cragmaw sites and the Redbrand hideout also had multiple entrances.
I've run the module 3 and a half times without really getting bored of it. I think a lot of the reason for that, other than bringing in different material from Icespire Peak or my own imagination each time I run it, is that the central locations all lend themselves to enough variety of approaches and resolutions that they remain fun to run for different groups. My only major critique is that since it is intended to be beginner DM friendly they really should have had specific instructions and supports for what happens when an enemy raises an alarm at one of these locations, because literally every group I've run it for has had at least one of these locations turn into a giant them vs. nearly every enemy in the location battle, and trying to figure out what all the enemies are and what they would do on the fly sucks.