Sending one high SAT II (800) only OR one high (800 MATH) and one low (720 CHEM)?

I have 1530 SAT, 3.93 UW GPA, 4.27 W GPA. What do you think I should do about the subject tests?

Depends what the school requires/recommends as far as SAT2’s are concerned. I don’t think a 720 in Chem is going to hurt you. For schools recommending 2 SAT2’s, just submitting 1 score will almost definitely hurt you more than submitting both scores.