The experience I had with Pokemon Gold in 2000 was revelatory, and is really the reason I keep playing the main series to this day. I want to try to recapture the fun I had while playing it back then.
What did it for me was how there were a very good balance of new and old Pokemon, and how the old ones that were in Johto were some of the better designs from the original games made me think that they were really trying to refine the experience from Red and Blue. And when I beat the Elite Four and found out I could go back to Kanto and beat the original 8 gyms again I was enthralled. There haven't been too many moments like that in videogames for me; realizing that I was only halfway through a game in which I would have been satisfied already was a great feeling.
Thus, I expected bigger and better things when Ruby and Sapphire came out in 2003 for Game Boy Advance. I wasn't really interested in any of the new Pokemon, really. I was interested in how they would change the main game, and I was thoroughly disappointed. They stripped out the additional 8 gyms - you only had the 8 new ones they introduced in Hoenn, the new region. What new Pokemon were there seemed to be repeats of old Pokemon, and really the only thing I liked about those versions were the fairly involved quests to get the legendary Pokemon - they had entire areas devoted to getting them.
I played the FireRed and LeafGreen remakes a few times after Ruby and Sapphire and liked them well enough, but have since largely forgotten them. There was quite a break for me in regards to Pokemon until I bought Diamond in 2007 and delved into that game. This post from 2008 about how much I still loved the game a year after it had been released is basically what I can say about how much I liked Diamond.
So fast forward to 2010. Remakes of my favorite Pokemon games have come out, and I have purchased HeartGold. I didn't think I would be, but the Pokewalker excites me. I don't know what it is - I suppose the fact that I am raising Pokemon while working or rollerblading or whatever really makes me happy or what, but I love that little thing. I already even know how to change the battery in case it dies! As far as the game itself goes, I've only beaten two gyms so far and am playing Etrian Odyssey II much more since I got it last week. I'm not sure why, but I think it's because I'm getting very tired of the core Pokemon game experience. I've just done this same quest so many times (and I mean not just in Johto - all the Kantos, Hoenns, and Sinnohs all bleed together to me) that I just don't really care about beating Gyms any more. At least not right now. I would like to murder Red on top of Mt. Silver, and I probably will. I just think I'm going to play through this Pokemon much slower than I've played through the games in the past.
Strange Journey comes out in three days, but I'm not sure if I'll play that right away or hold off and beat Etrian Odyssey II first, since I've already started it and the games are very similar. I think I might need a SMT break as well, so I'll probably beat EOII and the Edgeworth game before I break open Strange Journey. I guess we'll see! After Strange Journey, it will be a while before I feel the need to buy a game at full price brand new for a long while so that will be nice on my wallet!