I've been trying to figure out the staking myself having picked coins up for the first time recently.  It's a nice system.  Smartly designed to ensure a secure network.

The max stake is 16.18 which is small, but the interest rate is incredibly high so it's difficult to optimize your rewards.  For perfect efficiency the goal is to have each input stake right after it is old enough to give you the full reward.  In the case of a large input this is less than the min coin age (16 hours) so the trick is to find the sweet spot.

I sent coins to my wallet in both 1000 and 2000 sized blocks a couple days ago having scored a fair amount on that laughable dump to 200.  So far every stake I've gotten has been the max amount which tells me the inputs are too high.  So, I'm letting them split in half until I start getting stakes that are less than 16.18.  I can already tell that default coin optimized size of 618 is not going to be the sweet spot for me.  I've set the auto optimizer to 309 to start with and if that doesn't get me a few less than max stakes I'll cut it in half again until I start seeing them and then make a decision on where I want the inputs to be.  However, my gut says that it is likely that the guy who talked about inputs the size of 100 a few days ago may be right on the nose.

Anyway, hope this helps.  Some of you who are more math inclined could probably design a nice formula to figure out the optimal block size based upon your stake weight vs avg network stake weight, but I am not that person.  Personally, I'd think it'd be nice if Cedric could post something about this to make our lives a bit easier or even better, incorporate it into the wallet so it's figured out for us.

Cheers.