Another tip for a few grinding achievements
I've seen some people offering tips (the ancient city is a great place for several of them! well of souls for killing the snakes, etc etc)
I found that once you've completed the Bonus Level "Young Indy", and as long as you have most of the characters unlocked, there's a simple way to do a few of them without leaving the college, meaning you don't have to wait for the loading screens.
In Indy's office (the second door on the right in the college hallway), there are spots to blow up objects, to dig, to perform the academic talent, and to activate a thuggee. Complete all that you need then head across the hallway to the video room. The "Young Indy Outro" video is only a few seconds long, and once you watch it, Indy's Office will reset so you can do all of those again.