I'd like to make the observation that when I first joined the forum, I needed an ID on a woody plant, so I put my question in the Tree/Shrub forum. It *could* have been a lilac or a fruit tree (but it turned out to be an elm tree sapling). To me, it seemed to be the most likely place to put the question. And as some people have pointed out before, "experts" in the various forums tend to check their own favorites first and are more likely to be able to ID the plant in question. (Although my usual habit is to click on the search link for my own posts first, then on search link for "new posts since last visit"
Cactus/succulents -- I guess the difficulty arises since there is such a global readership of this website. From MY perspective, cactus/succulents are basically container plants!
Hmm, well, now that I've thought about it, I have a yucca, eastern prickly pear cactus, and hens & chicks in my back yard....
No help here on that account. May be easiest to have their own forum.