I like the idea about contests, I'm not very inventive when it comes to such things but in-game item prizes could be an incentive. These days there is far less planning revolved around the forum than in the past; this isn't a problem for us but there are obviously people who want to at least do 5-mans or even actually raid. Although it can be said it's their own fault if they miss out on a raid I do feel as though encouragement to find out what is going on should be looked at. Quite often people ask if anyone is interested in an instance to be met with stony silence that harks back to the pre-TBC days: "put it on the planner!!". With Northrend instances being shorter, I know imprompu runs are much easier than they used to be but if you are like me you want to know when you are going to have to be focused on the computer.
In the end I honestly don't know how many people this affects (it's hard to tell with the bazillion Alts in the guild, mine included), it is true that most of the active characters are just Alts of regulars. If you generally feel that it's not a problem then we can just let it be.
On a related note, could I also make a suggestion (guess this is the place for it). I was wondering if there is a way to have the Instance Planner slap you in the face in some way on the Home page. I don't want to seem picky or ungrateful because I know a lot of hard work went into the forum, but the little raid planner button doesn't even display in classic view (which I use - how it came to my attention).
Oh and I wouldn't think the occasional MotD would annoy anyone