How about:
Regular camera advantage is taking pictures without the temptation to share right away
Spare batteries for GPS.
If you can take the extra weight a prosumer/super zoom is nice to have. This does give better than cell phone camera pictures and the 12-20x zoom is like having binoculars. Ours is a Canon S3 IS.

I also like to have some redundancy in complex gear. So my cellphone has a gps and camera and I have a spare battery for it, I also have a standalone camera and gps. I prefer to keep the cellphone padded safely inside and thee standalone devices out and in use, so if I drop one in I don't loose my phone.