I also believe, due to the nature of content and the pacing of the story in Rohan, that RP/Story nights could be more regular. I like Lir's suggestion, for example.
There are no group instances in particular that I, personally, would like to delve into much between now and level 100. The Erebor cluster might be interesting at 85 as there is one Raid (The fires of Smaug) that we haven't done before and the cluster's content might drop unique items that are handy for gearing up for same level. At 95 there are Epic Battles of which I have done over a thousand...
Warbands are an option but I think we can clear all of them (group ones) in one sitting.
Yours Best ;)
"What we do in life echoes in eternity"