Need to decide between the two (before May!). Interested in science field of some sort but want the small LAC feel. I plan to go on to post-grad education. Have done overnight visits and like the vibe at both schools. Carleton will be a little more in loans (probably about 2K more / year). Unfortunately I will be taking out a fairly sizable loan for either school beyond that. I am trying to determine if Carleton is worth the extra money. If you graduated from Carleton, do you feel it gave you a leg up for grad schools or future jobs? Also if you attended one of these, especially in a science field, how much help did you get from profs if you were undecided about your specific direction/degree?
I really like both schools a lot. My kids decided on different schools but both were options for our family. However, Carleton has much more name recognition and it is very top notch for the sciences.
The schools have two very different vibes to them. I would think you would get a good indication as to where you fit in after having visited both. My daughter is just coming back from her admitted student day at Saint Olaf, and liked it very much. She was also admitted to Carleton, but felt that the academic pressure might be just a bit too intense on the quarter system. They both have great science facilities.
Someone just started a post about science at LACs. The second chart shows PhD production from 2004 to 2014, and Carleton was no. 1. St. Olaf had about half as many.
I think Carleton is worth $2k more/year, but how much are you taking out total? Are you sure that you can afford either of these schools?
2K difference per year over four years, IMO, is not that great a cost difference, maybe 3-4% of full price at each?
If relative prestige is important to you, Carleton has more name recognition nationally and is more competitive with respect to admissions rate, I believe. But both are respected, especially in the sciences and both have a strong record in placing students into graduate programs.
Do you have other options that don’t require large loans?
2K a year is not that much of a difference in the overall cost. If you prefer Carleton, go there. But I can understanding preferring St. Olaf, particularly if you want to participate in music. I also think St. Olaf’s campus is more beautiful. Carleton definitely has the edge in reputation/rankings. They are both great places.
I’ve toured both multiple times, my cousin went to Carleton and I’m going to St. Olaf next year (they gave me a lot of merit aid) so here’s my take. If you’d consider yourself a hippy or a geek you would fit in better at Carleton. If you’re more preppy or if you like people who you would consider “normal” you would fit in better at St. Olaf. What sort of science are you interested in? I’d say that the biology may be better at St. Olaf while computer science is definitely better at Carleton. I chose St. Olaf because being on its campus makes me feel happy and energized. The buildings are gorgeous and everyone’s smiling and friendly.
Consider other factors like location. Another thing to consider is how easily you can get the courses you want at both schools! You can’t make a wrong decision here.
“Consider other factors like location”
Like which side of the town of Northfield you like better? 
Carleton more laid back, quirky, and greater variety of students geographically and socially.
Olaf more conservative, more homogeneous, and somewhat larger.
Carleton has stronger rankings nation-wide, but both excellent in science education.
$2K per year is peanuts in the overall cost. Go to the school you want to attend, and where you would be most happy.
No bad choice here—at all.
"“Consider other factors like location”
Like which side of the town of Northfield you like better?"
Carleton much closer to the Reub 'N Stein, as well as the municipal liquor store. Important locations when I attended back in the stone age. 
The Ph.D. Production comment is a bit misleading because the student doesn’t plan to major in ever subject leading to a Ph.D. For life sciences, for example, Carleton AND Olaf are both in the top 6. But you’re splitting hairs because they are BOTH excellent schools. And outside of the Midwest you’d really REALLY be hard pressed to find someone who says either school off the top of their head.
You say one costs $2k more but both require substantial loans. How much $?
Our DD got a sizable merit scholarship to Olaf and none to Carleton (they don’t give them). It’s not worth twice as much to go to Carleton, but if the difference were $2k AND it fit you, why not?