Just my .02 on character DLC; (BTW, Im in the "cure/extend Thane's life" camp, so you all can guess where my feelings lie.......) if the DLC(s) in question are more "story" related, instead of character specific, then you can ADD a fair amount of quality character content as an extra. This would then mean it is accessible (and desireable) for ALL kinds of players, and makes the replay of said DLC, go up. As for the type of extra character content, it could be in the form of "well, this character had a relation to this story line, or new group of NPC, so they could have more content to reflect that connection. Then, you can add some nice romance fluff (characters referring to your LI of choice, more personal romance dialogue with your LI, showing of affection, ect......ya gets the idea!) that is excessible to all LI's that are available in said DLC (for example, if you do have a story line that is more ME2 squaddie heavy, then perhaps the focus on the ME2 LI's would make sense...then if you have another story DLC that focus' on the current crew, those might have extra LI content).
By not making it character specific, you don't run the risk of some character DLC not selling well (which is unfortunately a bad business setup, and thus could be problematic to implement.) I am aware that Liara had a DLC specific to her in ME2 that worked, but because of all the variables they have to work with, the "character specific" DLC could be tricky to do.
This isn't to say that the specific character content that I mention above will be just a few tagged on lines or something; I do mean real quality content. The outline for something like this already has been implemented before with DLC. Take for example Legacy and MotA in DA2. Both DLC's have some character specific moments (ex: in Legacy, both Varric and Anders have extra content, but you are not required to bring both of them.....still, this extra content exists. In MotA, Aveline and Isabella have extra content......). In both DLC's ALL the characters have new banter lines, and moments of interjection. And characters you can romance do have romance banter that comes up (i.e. Fenris saying how you frightened him in MotA when taken by the Duke, or in Legacy he will talk about the"night" your Hawke and him spent together) Now, this could be even deeper/richer that that, but it gives you an example of how it could be done. The question now is; will it?!?
**And just an aside; I really want them to offer us a choice to cure/extend Thane's life. This could be implemented in a few ways (I have posted a few ways they could do this that would NOT interfere with the base game), then fleshed out as extra character content for him in one of these story DLC's. This way those that wish to save/extend his life can, and those who don't, well...............ya wuteva.