I've only listed stuff I've actually played, there are some shooters and stuff that other people seem to have enjoyed in the form of Resident Evil Revelations. I also have a lot of love for the Phoenix Wright series, as well as the Zero Escape puzzle/choose your own adventure game, but I understand they're not going to appeal to everyone.
There must be some way to develop nostalgia retroactively!
Sure it's part of the reason I like Nintendo stuff, but a lot of it comes down to first party stuff being really well polished, and fun to play. Like you, I kinda lost interest in Pokemon X, despite adoring Red and Blue when they came out, so I'm not sure if it is the love of the series that carries those games. I'll probably try and pick it up again at some point.
As for going back, I'm not sure, maybe? You could cheat by picking up some of the re-releases of older Nintendo properties I suppose, like the Ocarina of Time remake (though this one was carried pretty hard by nostalgia for me).
As for recommendations, what sort of stuff do you like?
From my (limited) experience with Fire Emblem games, the one's I've played prior to awakening can be pretty brutal (they're also difficult to get hold of here in the UK).
I've played (don't think I managed to finish) Fire Emblem: Path of Radiance for the Gamecube and Fire Emblem: Radiant Dawn for the Wii. They're fairly similar to awakening, as in you'll know what to expect going in. But I feel they can get downright unfair at times, the guys they give you at points in Radiant Dawn are made of paper or something...
If you enjoy a challenge (you can still turn your dudes into demi-gods and stomp the game) then by all means seek them out. I seem to recall Path of Radiance being on par with awakening difficulty wise.
But Fire Emblem Awakening is definitely the most fun I've had with the series, so you might be a little disappointed if you decide to go back? Or I dunno, maybe I'm just a filthy casual (it has been a while since I last played the older titles).
Pretty sure there are some Fire Emblem experts on this board that will set you straight.