Don’t you have to decide by 5/1? Ideally you would revisit both schools, as I believe they are quite different. Check out some of the recent threads in this section, particularly the one about visiting days, for some insights into Grinnell.
As for isolation, yes, you need to drive through and hour’s worth of cornfields to get to Grinnell from Des Moines or Iowa City/Cedar Rapids, but the town of Grinnell is quite pleasant and the campus is rich in resources and activities. Kids do go to nearby cities for concerts and such occasionally, but don’t need to.
collegedata.com has some basic stats that can give you some basis for comparison along various lines. Grinnell is more diverse and its kids have on average higher stats, but look for the things that matter specifically to you – majors, activities, etc.
Some very recent impressions of Grinnell here:
http://talk.collegeconfidential.com/grinnell-college/1985584-grinnell-what-is-admitted-student-day-like.html#latest
This very old thread … updated recently … is still accurate.
http://talk.collegeconfidential.com/grinnell-college/438138-why-grinnell.html#latest