As someone who recently graduated from law school 2 years ago and who worked at a top firm second year summer and then after law school, I would recommend that you look outside firms for 1L jobs. That's what I did, and the fact that I had worked for a non-profit organization my first year summer helped me immensely in OCI second year first semester. The bottom line is this: you need to go to the place where you'll get the best experience, the most opportunities to write or the most opportunities to go to court--not where you'll get the most money. This will pay off immensely later on. It will also make you stand out in the OCI process because you'll have more interesting anecdotes and you'll also end up with better writing samples, trust me!
Besides that, it also will ensure that you don't get a one-sided view of what you can do with your law degree (it's almost impossible to get a job at a firm if you don't work for one your second year summer, but firms don't really care if you worked for a firm your 1L summer, so doing something else during that summer has no bearing on your after graduation prospects). This means that 1L summer is a good time to get a feel for something besides the firm environment so you'll know whether it's something that you really want to go into for the long-term.
This is just my two cents, take it or leave it.