Hi! I've been looking at the latest threads and I've been wondering: What do the fans consider to be the very best ideas that the Castlevania series has had?
We can probably place these in 'ideas good at the time of conception', 'ideas that are always good', or something.
I will start with my own list, and you guys can add to it, or debate whether my ideas are good after all (I'm putting 'em 'cuz I think they're pretty good).

Ideas that are always good:
-SubWeapons use a separate button, rather than UP+Attack.
This allow you more control, as you can fire them while crouching. Used in Bloodlines, Super CV4, and CV64/LoD.
-Branching Pathways
This gives you a more vast castle and adds an exploration element. I'd prefer if the branching pathways took you to separate stages altogether, but it's also nice when you can tackle the stage itself through another part of it. Used in Castlevania III (to an extent), Rondo of Blood, Castlevania Bloodlines, Metroidvania stages, Rebirth.
-Multiple Characters, that team up
This is probably one of the better ideas, and one of the reasons Castlevania III is very popular. Having a team of people of which you can choose and switch someone is great, especially when they have varying abilities (or even varying subweapons). It is a tried and true good idea, in my opinion. Used in Castlevania III and Dawn of Sorrow (Julius Mode) and Portrait of Ruin.
My favorite method in this idea is when you can switch between them, not necessarily when a character follows another, so I'd prefer something like CVIII or DoS rather than PoR.
-Multiple Characters in Single Mode, with relevant plot
This was done in Castlevania Bloodlines and Rondo of Blood, and came back with CV64/LoD and Sisters Mode PoR, and Julius Mode DoS. I'm fond of playing the game as another character, but I'm not fond of the game just throwing that character into the game with no plot at all (I'm looking at you, SotN, HoD, LoI, CoD). If you're gonna put in a playable character, give them some story if the game uses story. Don't just plaster them into the game. It just seems like an afterthought at times.
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Ideas that were good at the time (they may not be so great at other times, but at the time were a welcome addition):
-Sprawling Map, Metroidvania Style
After Super Metroid, when Symphony of the Night came out, this was a welcome change to the franchise. However, it has been so used (and possibly misused) that now it's just an expected thing. Though I generally like it, it was a welcome change to see the "Hub" setup (like in LoI), or how they did with Ecclesia and added stages to a map, etc.
Ideally, I'd like how Simon's Quest did it. You have multiple connecting mapped areas but you also have monster 'lairs' (like the Mansions) that have their own stage. However, everything is connected.
-An Array of Weaponry
Once Symphony of the Night added RPG elements, the sheer amounts of weapons, armor, shields, helmets, and accessories became a staple of the series. While for an Action RPG this is generally a great idea, I don't think it needs to be so vast of an idea for CV titles. I think this appeals more to the people who like to loot and plunder, or to the people that like to grind for the best items... it's OK but I don't think it's a necessary thing for Castlevania to have.
Anything you guys wanna add?
Do you think Summons (SotN, CotM) were awesome and should return?
Did you enjoy climbing on a boss to reach its weakpoint (Eligor from OoE, the Titans from LoS?)
Maybe you enjoyed Devil Forging?
Try and categorize your ideas if possible.