Pros
There's a good group of people that stay and work during summers. I didn't live on campus, which freed me from the bubble. Pretty relaxed environment, as long as you get your work done, bosses usually didn't care how it got down. Plus, you get to meet a lot of staff and professors that you may not have met before. Overall, if you can't find a swanky job elsewhere, there's no shame in staying and working on campus. In fact, I learned a lot and made a solid amount.
Cons
If you've already gotten sick of the Carleton bubble, staying all summer may not be the right choice. You should really have a car so you can do fun stuff after work or on weekends. The experience is also what you make of it. Some people don't do anything all day and make the same hourly wages... it can be frustrating. But remember that your bosses genuinely appreciate hard-work and will reward it with good advice/hours/job recommendations.