[Award Advice] ATL-BCN using UR for upgrade to Biz

Hello, looking to travel ATL-BCN end of Apr/beg of May. Have about 150k in Chase UR points and wondering whether my best option would be to use points for 2 economy tix and then be unable to upgrade, or spend on economy and use points to upgrade to Biz if possible. Hoping for the latter but could use advise and guidance around which airlines would be the best bang for the buck in my situation. Willing to spend on discount Eco and upgrade using UR. Thanks!