I bet easily 75% of my potential subscribers don't even have a CLUE what features the premium subscription DOES offer...That's what Im' feeling for ideas on.
Until your big idea hits, you could try some marketing on the cheap:
(1) To initiate their free trials, present members with a listing of the 10(?) Premium Features, and ask them to rank those features 1-10 according to how useful they expect to find them during the trial period.
(2) Immediately after the free trial, ask them to rank the same features again.
You might find a significant difference between expectation and experience. You might find none at all. For your purposes right now, that is a secondary consideration.
What you will have done is (a) introduced new members to the Premium Features prior to the trial, (b) reinforced the features as benefits after the trial and (c) encouraged new members to give those features at least a modicum of consideration before, during and after the trial.
Market Data 
Markets 
AI
