People think they can succeed without even realizing you need a proper foundation to build anything worthwhile....and that foundation has been, and always will be, Geometry and Algebra. 

Assuming the neighborhood doesn't change substantially and still warrants a 15.6 GRM on its buildings, you should be able to sell the property for $2.5M ($13,4000/month x 12 months x 15.6 GRM).So if you bought at $1.5M, spend $900K on the renovation and ADU build, then sell for $2.5M, you haven't really earned that much for your efforts.So, yeah, these improvements don't seem worthwhile at the prices you've been quoted, but again, your quotes seem wildly high.

I'm not so sure properties with balances closer to the market value of the home will be as worthwhile though. 

If you do the work yourself it is much harder for it to hold up in court.But just becuase you can doesn't mean it is worthwhile. 

Home prices are much higher in 2024 than they were in 2010 so hopefully you made a good amount of appreciation on your investment.It may be worthwhile to sell, if possible, within the next couple of months if you want to take advantage of section 121 exclusion becuase it looks like it will expire for you soon.

If you do end up investing close to where you live, it is worthwhile to manage your own property for a short time.

Yes, HELOC financing isn't as cheap as owner-occupant or even investor financing, but the leverage can still be worthwhile......because the fundamental cap rate of an ADU is SO FREAKIN' HIGH.

If I'm selling a property right now, is it worthwhile to hold off until 2H 2024 when fees go down?

I have not found it worthwhile to have a property manager on short term rentals.

It might be worthwhile to keep son and daughter off title and just have them mange them and run the business.