<p>My first, quick thought: you will be happy in either place. There is no bad outcome here. There are two good outcomes.<br>
I don’t quite understand your concern about Swat only requiring 12/32 courses being in engineering and that being a problem…couldn’t you just take more if you wanted? Who cares about anyone else?
Finally (and here I’m revealing my small school bias), if you feel you would be comfortable in either setting, and if you see advantages in both the 7,000-student and the 1500-student experiences, and you plan to go to grad school, why not choose Swarthmore? Your grad school will almost surely be of the large research university variety.
Good luck! May all your life choices be similarly no-lose :)</p>