Of the two, which has a better undergraduate physics program? Factors I am considering are research opportunities, quality of faculty, financial aid available to internationals and campus life.
You can look at each school’s catalog and schedule to see what junior/senior level physics courses there are and how often each is offered. You can look at the faculty rosters to see what their research interests are. You can use each school’s net price calculator to see what its financial aid (if any) may be like for you.
for physics maybe http://physics.lafayette.edu/program/ would be a better choice.
Wesleyan has the advantage of having a small graduate program in physics (15-20 students), which means all the research opportunities of an undergraduate liberal arts college combined with the high level physics of a research university.
Wes has had great success recently with the Leroy Apker award (the recipients are chosen for “outstanding achievements in physics by undergraduate students” in order to “provide encouragement to young physicists who have demonstrated great potential for future scientific accomplishment.” The Apker award is the highest honor awarded to undergraduate physicists in the United States, and only two are chosen each year).
Wesleyan has had two Apkers winners and two Apker finalists in the past 10 years… despite having to compete in the Ph.D.-granting-institution category (directly against schools like Harvard and Berkeley) because Wesleyan has that small graduate physics program… but it’s the undergrads winning the award, so it’s not like the Ph.D. students are gaining all of the recognition.
http://www.aps.org/programs/honors/awards/apker.cfm
Swarthmore (and Lafayette) haven’t had nearly the same success (in admittedly just this one metric).
Very different schools in size, locale, student body and atmosphere. Both will provide a strong physics academic environment. Look beyond physics for your answer. (Why these 2 particular schools?)