Looking for some advice - Sophmore majoring in economics

Im currently a sophomore majoring in economics at a target school (top 5) but I've been unable to land any finance internship. Up until now, my focus was on marketing but I've been a bit disenchanted with the field and would like to get into a finance/econ/statistics job after graduation. I think the most likely reason I haven't been getting any finance related internships is (1) I have a 3.2 GPA and (2) I don't have any finance background at all other than my econ major.

However, since I have a lot of experience in marketing, I've been able to land a marketing internship at a very prestigious advertising firm in San Francisco. Up until I got the offer, my plan was to take summer classes (hopefully boost my gpa up to a 3.3 or 3.4 starting junior year) and doing econ research on the side. I'm not really sure what I should do.

Pros of Marketing Internship
1) Real work experience at a highly reputable firm in the advertising world
2) Paid
3)In San Fransisco

Cons of Marketing Internship
1) Not a field I want to go into after graduation
2) Don't want to continue pigeonholing myself into this field

Pros of Summer Classes/RA work
1)Boost GPA up
2)Learn statistical skills like STATA, R, etc

Cons of Summer Classes/RA work
1) Missing out on work experience at a company
2) Tuition (although this isn't too big of an issue)

I guess my question is how will banks/companies view this marketing internship? Will they see it as a positive because I'm getting work experience in or will they question my desire to work in finance?