I made a stock of 1 mg/ml DAPI from Sigma (D9542-1MG) in water and used 1:1000 dilutions incubated for 3 nights for mouse brain hemisections at room temp. For 1 mm sections I use 1:500 for 1-2 nights. Attached is a confocal image of a mouse brain hemisections viewed from the midline.

I find the DAPI staining to be very reliable. Depending on the speed and the volume of tissue I stain using 1:100-1:1000 dilutions over 1-3 nights.

Good luck!

https://drive.google.com/file/d/0B8x-dn53Sa7NQ1FsNDVWT3ZnaGc/view?usp=sharing