This is such a great thread, I wish I'd had it to read a year ago when we were first nightweaning DD. Just a few thoughts on specific posts here (I'm too lazy to figure out how to quote multiple posts, so bear with me please!)...
1. Tantrums: Just want to add hand to those who's kiddos had severe, heartbreakingly distressful reactions to weaning. The first time we NW'd, she did pretty well, mainly regular crying and some flopping around in her crib, but for the most part it wasn't so extreme (and that was both ending co-sleeping and putting her in her own bed/room AND nightweaning, so it was a lot of transition but NW without putting her in her own room seemed impossible for us). Then we travelled, backslid on the night BFing because if we'd not done it she picked up quick that we were worried her tantrums would wake everyone in our hotel/friends' houses up and we didn't want that so we caved and I nursed her. That was a week-long trip, and then she got sick when we came back so it was another week of nursing her through being sick, then we travelled again so by the time we really started to NW again, we had backslid for about a month. This time was SO MUCH HARDER/EXTREME. It was awful, she got so hysterical she'd try to bang her head against the wall and just cry and scream in a way I was sure a neighbor would call child welfare on us since it was almost every night for a couple of weeks. Eventually we got through it (with help from a child psychologist who specializes in infant/toddler sleep problems and also a lot of love love love for her and ourselves). THEN another several months later I travelled again, and while I tried to plan to sleep apart from her for the whole trip, our first night we ended up having to sleep in same bed in what turned out to be studio apartment of friends' where you could also hear the upstairs and downstairs neighbors. Deja vu. Backslid again.
In the end we had to combine nightweaning with full weaning this last time (when dd is 2.5 yrs) because I was in an accident and taking meds. It has been hard as heck, harder than either of the other 2 times, because a) it's FULL weaning, b) it's cold turkey, and c) she's SO MAD AT ME. She understands why we aren't doing nursies, and talks about it when she's awake and calm, but at times we'd usually nurse she cries at the sight of me, screams for her daddy, and just breaks down, sometimes for more than an hour. I try to just stay with her, hold her if she lets me (which she rarely did), and love her through it, mostly letting her direct how I needed to be there. Now (5 weeks later) we finally seem to be heading into stable territory and she's not as mad at me, wants to be held by me when she's upset again, and even asks for me when she wakes up (for 4 weeks it was "DADDY!!!" which of course DH was happy to finally be the "needed parent"! ;) )
2. Stories our babes tell themselves about the end of nursing: While DD understood I was injured in the accident (including facial injury so that actually helped make the reason for weaning more concrete for her), and that I was on meds, she extended the reason for not nursing to also be that my milk was "spicy", because she hates really spicy food. So she still occaisionally looks at my boobs and says "No nursies because it'll make me sick! It's SPICY! My tummy will hurt!" I just thought that was so sweet and so interesting, that she took what for her was the worst thing a food/thing could be (spicy) and added that to the reason for weaning.
3. Processing the loss: someone mentioned it helped for their DC to look at her breasts and be able to touch and talk about them. DD does the same. I try to almost always have them covered up (having them exposed feels like adding insult to injury during this transition) but on occaision either she'll catch me coming out of the shower or she'll reach in and pull them out, then she does what we call "Nose Nursies" and rubs her nose on my nipples or just cuddles them. It's sweet and kinda makes me want to cry, because I miss that connection too. And it makes me proud of her, because she's kinda joyful when she does this. We do it, laugh, I take it to extremes (ear nursies, underarm nursies) and she laughs and then I distract her and put them away. It seems to also really help her say bye bye.
Good luck to anyone still facing this/going through it now. I definitely agree with all who said you have to make your mind up and be clear in your heart that it's what's best for your family overall, that will help you get through it. And I'll share that even in her worst tantruming stage, the psychologist we worked with said her reactions were normal, and that we werent' hurting her, which we really needed to hear from someone outside of our support system. I'm sure there are traumatic ways to handle this, so I'm not saying there aren't probably bad things that someone might do, but if you're doing it from a sincere place and extra-loving your child and yourself through it, it seems like it can work and be ok if not better for everyone if it is really time to do it.