Played a lot of Warcraft 2 and 3 and was super into all the lore. First time I played Vanilla World of Warcraft in the beta and just seeing all the places up close that were super zoomed out in the RTS games had me completely immersed.
Most memorable would be walking into the Valley of Heroes in Stormwind the first time and having the music hit. I just stood there listening and looking at the statues for a good 15 minutes soaking in all the ambiance.
Former and current WoW junkies feel free to chime in :>