While on vacation last year with my gripped 30D, I took about 1600 pictures before the batteries died. And that was on a used camera with used batteries I purchased a year ago.
So, when I, too, upgraded to a 60D (and bought a grip as well), I figured about 1600 pictures as well before they died. I think I ran it up to about 1200 before I 'chickened out' and recharged the batteries. I don't have spares. I figure the battery charge level in the viewfinder is a pretty good indicator of how many shots I have left before the die, using 1600 as a 'full charge' amount (with the grip). The day before I go out to do some shooting, I double the estimate of how many shots I'll be taking and check to see if I have enough battery left to handle it. But, of course, on important events, I always leave home with fully charged batteries.
I forget how I 'found' it, but there's a menu info screen that shows number of shots per battery, and if I recall, an estimate of how many shots left.
Of course, using the popup flash, Live View, or longer LCD display time or longer shutdown time will drain the battery(s) faster than the calculated number of pictures based on power/charge level.