102 stars, or 85% complete.

Let's see if I can remember what I got... I got 100 coins in Dire Dire Docks, which completes that level. There seems to be just barely enough coins to get it. (There might be 103 or something total, but I left a few near the drain to the moat, since I got sucked into that on the previous attempt).

It seems that you can only do the Bowser's Submarine star once. That sucks.

I got the 8 red coins from Bowser in the Sky. The only Castle Secret star I need now is wing Mario over the rainbow.

FO thinks Bowser in the Fire Sea is harder. Hmm... I'm not sure. The second to last red coin in Fire Sea takes more timing than anything in Bowser in the Sky. But it seems more red coins are hidden out of sight in the Sky.

I got two stars in Rainbow Ride. One was something like Tricky Triangle Jumps. The other was ... Swaying in the Breeze? Anyway, both of them are reachable through a shortcut from the beginning of the stage.

While I didn't get the red coins from Wing Mario Over the Rainbow, I did activate the cannon.