Nexus:
You can jump behind the wall that's just below and to the right of where you enter the boss room. This is almost totally safe during add spawns, but killing the boss from here takes FOREVER so between add waves I recommend jumping out.

I haven't tried it on Nightfall difficulty, but I find some of the geometry on the level is fairly safe to stand on where Sekrion doesn't really have a way to shoot at you. You still have to worry about adds a bit though.

Why would you cheese (a word I'm still learning the definition of) when you could have fun?

I feel I reply with this answer far too many times:
"You cheese in Destiny because it LEADS to more fun".

Why did I spend hours at the Holy Cave? To get a legendary weapon which SIGNIFICANTLY increased my fun in the crucible and PvE. Why did I cheese the Arkon Preist? Because it gave me Gjallahorn which is BONKERS FUN! Shooting my Gjallahorn and watching the wolve pack rounds annihilate everythign nearby gives me an inordinate amount of joy.

If Bungie is going to put the "fun" things behind RNG and monumentally difficult (read: unfun) tasks, then yes I am going to cheese them.
Nuf said.

You will be OK if you are high level enough to kill Sepkis fast perhaps before the (3rd?) Wave starts.

As for hoops, beating a level before you get to the next one is a hoop.

This isn't true. A level is a challenge. You've mastered the challenge? Here's another challenge!

Each level is fun for its own sake. Getting to play level 2 after you play level 1 is merely the continuation of the fun. They are ordered because a well designed game gets harder and harder as players master more and more of it.

Yeah, that's exactly like I see Destiny.

As for hoops, beating a level before you get to the next one is a hoop.

This isn't true. A level is a challenge. You've mastered the challenge? Here's another challenge!

Each level is fun for its own sake. Getting to play level 2 after you play level 1 is merely the continuation of the fun. They are ordered because a well designed game gets harder and harder as players master more and more of it.

Valus T'arc:
Back left corner from where you enter the room is an area blocked off by a bunch of crates and a ramp. You can jump in between the crates and back wall or the ramp and the wall and cheese from there. Room for the whole fireteam!

I just wanted to add that there's another similar area under the other ramp, on the same left-hand side of the room. If it's clear enough on the outside, you can move between the two when Valus moves from one end of the room to the other, so that you can still hit him. Or, with more than one player, you could just have someone stay at each end.

Why would you cheese (a word I'm still learning the definition of) when you could have fun? Letting the investment system alter the way you play is your choice, not Bungie's. All the loot and bounties, etc. are just incentives for me to go have fun.

Because, engaging with the investment system is tied to your ability to have fun. Go run the raid on hard without gear and tell me how much fun that is. I don't want an incentive to have fun: just let me have fun. The investment system is a hoop to jump through before you can have fun.

I didn't need Destiny's investment system for incentives at all until after something like a month or two of playing. Now that I've spent so much time in it, I like having something to point me in a direction to jumpstart my own path. If ODST had come with some daily bounty things, it would have extended the life of it for me, because after I had run out of ideas after many playthroughs, I would have had a little jumpstarter tool to help inspire me to find more fun in places I hadn't tried before. Reach's campaign challenges sometimes led to a lot of fun after I had already played levels to death on their own, and I wasn't doing it for credits to buy armor.

Sometimes I can sit down and draw something. Sometimes I need to look at a book or a magazine to inspire me. That's what Daily Missions and Bounties are to me.

As for hoops, beating a level before you get to the next one is a hoop. Or any game that has any unlocking moves, weapons, etc. So something like 90% of all games ever made have hoops. And Destiny's hoops don't get in the way of my fun. I've never tried the Raid on hard because that doesn't sound like fun to me in the first place, personally.

This is how I play the game.

1. "What should I do today?"
2. Go look at bounties, dailies, find something to do.
3. Go do that, usually get into some kind of hijinks or distracted by something else fun.
4. Turn in bounties and upgrade stuff if I can and go to sleep.

This is amusing, because the bounties are all unimaginative filler bullshit :-p

Well, I'm glad my enjoyment is amusing to you? I... guess I'm too stupid to realize the filler bullshit I'm steeped in?

Why would you cheese (a word I'm still learning the definition of) when you could have fun? Letting the investment system alter the way you play is your choice, not Bungie's. All the loot and bounties, etc. are just incentives for me to go have fun.

Because, engaging with the investment system is tied to your ability to have fun. Go run the raid on hard without gear and tell me how much fun that is. I don't want an incentive to have fun: just let me have fun. The investment system is a hoop to jump through before you can have fun.

This is how I play the game.

1. "What should I do today?"
2. Go look at bounties, dailies, find something to do.
3. Go do that, usually get into some kind of hijinks or distracted by something else fun.
4. Turn in bounties and upgrade stuff if I can and go to sleep.

This is amusing, because the bounties are all unimaginative filler bullshit :-p

This is how I play the game.

1. "What should I do today?"
2. Go look at bounties, dailies, find something to do.
3. Go do that, usually get into some kind of hijinks or distracted by something else fun.
4. Turn in bounties and upgrade stuff if I can and go to sleep.

The point of the game for me is number 3, not number 4. I think humans just tend to naturally get addicted to rewards and lose sight of the quest - the thing that makes the rewards mean something.

Devil's Lair:
Not really cheese, but you're safest in the room to the left of the entrance to the boss area. Adds won't ever enter that room for some reason, though they'll still shoot into it.

Not always true. The other night I was going for a death-free strike and a captain came up the stairs behind me.

Winter's Run:
As shown in this thread, under the platform. There's also a spot on the rocky ledge where you enter the boss area where the enemies will rarely, if ever, hit you.

Nexus:
You can jump behind the wall that's just below and to the right of where you enter the boss room. This is almost totally safe during add spawns, but killing the boss from here takes FOREVER so between add waves I recommend jumping out.

Devil's Lair:
Not really cheese, but you're safest in the room to the left of the entrance to the boss area. Adds won't ever enter that room for some reason, though they'll still shoot into it.

Dust Palace:
This won't be a nightfall strike until Xboxers can play on it, so don't worry about it. Mostly you just stay on the back walkway and snipe - there's no cheese spot I'm aware of.

Phogoth (what's this strike called?):
Stay in the room before the room Phogoth is in and snipe from there. When the shrieker spawns (and yellow adds), run back to the previous room and wait for them to despawn.

Since there are such effective cheese spots for all strikes, I really assumed that Bungie designed them with cheesing in mind. I'd seriously love to see some Bungie videos of the *intended* way to defeat each nightfall strike.