Sooo, I already did a post like this, just moved it here. I don't know if these ideas are floating around already, but I couldn't get myself to read all of the suggestions, which I think are awesome as far as I read them. Here are my two cents.
1. Stats for staff - former idol
I would love to still be able to see the stats they graduated with, their earned money, accomplishments etc.
I think it adds a lot of depth to the staff.
2. Dating staff - former idol
Still being able to interact with the former idols, like going on a date would be great too, so you don't disconnect from your favourite idols.
Having additional lines as staff maybe?
3. Coaching / Styling skills - former idol
Having their coaching skills depend on the associated skill they had as an idol, so they can pass their knowledge on instead of starting from scratch, because they feel kinda useless in the long run.
I haven't encountered a former idol as a stylist so I don't know if that's even a thing, but if not, I would love to see it implemented.
I think separating the styles would be nice. Regular staff you can hire could simply have two of them at the same level, so it wouldn't change that aspect.
4. Motivation score
Maybe idols could start with high motivation, as new idols and lower it over time until 50% or something, because they become accustomed to their new lifestyle.
This could be accompanied with new traits, which impact motivation gain and loss.
Could actually impact if a graduating idol wants to stay with the group.
5. Punishment for minimum wage
I guess that's a beta thing, because I haven't seen any impact for them being unsatisfied.
Let idols provoke scandals, because they're underpaid.
Or even quit for good if the payment is far too low or over an extended period.
Maybe combine with my previous point and lower their motivation, or increase it to a certain degree with high payment.
6. Filter Songs in Concert Setup
Having the option to filter for fan satisfaction, stars etc. would be nice, because the song list becomes quite extensive after a while.
7. Sister Groups as opening acts
Maybe add the option of having a sister group as the opening act with a seperate setup to promote them.
8. Calendar
A calendar would be great to properly schedule tasks, concerts etc ahead of time.
9. Special event preparations
I think being able to prepare multiple special events in advance should be a feature, so they can launch after cooldown has reset.
This game is already great and has so much potential to grow. I look forward to the next update and will keep playing until then^^
* Structured and added some points.