"11. f4 I'd like to be able to open up the center, then (depending on where black's king goes), launch an attack."
Sounds like a reasonable plan, why not follow up with this on move 12 and play 12. e5.
The f6 knight doesn't have a good spot to go. For example, 12. ... exd5 13. fxd5 Ng8 it's quite unpleasant to put the knight back there. But 13. ... Ng4 gives white two ways to win, 14. e6 Bxe6 and now either:
15. Nxe6 Qxd1 16. Nxc7+ Kd8 17. Nxd1 wins a piece or
15. Rxe6 fxe6 16. Qxg4. Looks like a potentially deadly attacking position.
Looks like all this same stuff is still available after 12. Bxc4 bxc4 13. e5
23. Re4 and Rg4 was a good idea. But maybe you can involve the other rook immediately with 23. Rd1 followed by 24. Rd7.
I played this game against a good friend of mine recently. I know I blundered an advantage in the middlegame, but I can't figure out where exactly I went wrong. I have some idea, but any input would be greatly appreciated, especially in regards to my 29th move. Thanks!