Going to depend on the performance of your home. Usually, it will cost more to bring the temp down than "holding" at a reasonable temp while you are not there.
Remember, AC is not all about temperature, more importantly is relative humidity. When you raise the temp / RH it effects everything in your home, so you are not just reconditioning the air.
The holding temp will depend on your home. Some homes would never reach 80-85 in a day, others could reach it in a matter of hours. I would strive for a temp which allows the AC to run once or twice an hour to try and keep the humidity in check. Again, there is not a one solution fits all.