There's also the GBA and DS games to check out. My favorite of the handheld series is Order of Ecclesica, but it's a rather difficult game. Dawn of Sorrow or Portrait of Ruin would be a better option for getting into the handheld series. But I would suggest the previous ones I suggested first.
By the way, look up SomecallmeJohnny on youtube, he's got quite a few reviews on the older console Castlevania titles and their remakes, should help with picking out which games you want to try first.
Oh that's an interesting question. Castlevania is for the most part split into two different play styles, the 2D linear side scroller platformers and the Metroidvania games, which of course play very similar to the classic Metroid series. For the classic series I suggest Castlevania IV and my personal favorite of the classic series; Rondo of Blood for the PC engine.
Both games are fairly easy to jump into and far more forgiving than their stiff controlling NES brethren. You can find both games on Nintendo's Virtual console. For Metroidvania I suggest the first to use the formula; Symphony of the Night. It's one of my favorites and is incredibly fun to play, there is so much in the game, from the massive castle to the ridiculous amount of items to collect, it's also one of the smoothest playing games in the series. You can get SOTN on PSN, but it's also been remade for the XBL arcade. I would suggest the PSN version as a personal preference, but there's nothing wrong withe XBL version.
You seem to know a lot about Castlevania...I have a question I wanna ask you. I've been kinda interested in playing the games, what would be your top 3 recommended Castlevania games for a newcomer like me?