Are niche directories such as directories of directories or business directories generally less easy to promote or do they have qualities which make them more attractive to your average submitter? Also, how hard are they to sell compared to general directories? I am trying figure out the direction I should take a directory I am creating. Thanks!
Niche directories are more attractive to sites in that niche because the link will be more relevant. Also you need to search out relevant sites to advertise on for the same reason.
relevancy helps seo, so I would assume if you relate to that niche, it would be MORE beneficial than a standard directory, but you are losing out a lot of customers.
They take longer to establish and are harder/more expensive to promote because you have smaller pool of relevant places to do so. They are very valuable to submitters because of the strong relevance and I think generally you can charge more. Niche directories are probably a good long-term investment if you have patience and don't need them to turn much of a profit for a year or so. As far as selling there would be the same problems related to the above. Since it will take longer to build up traffic and revenue you will have to hold on to it for longer to sell it for a decent profit.
I prefer to get listings in niche directories. A good niche listing is usually worth more than a similar one in a general directory, because of the kind of traffic that listing will attract. But it's definitely true that they're harder to get submissions for, and you'll get a lot more off-topic submissions.