This is a Sunday brunch with the guys or family outfit! I feel like you don't have to wear dress pant to wear a blazer with a dress shirt. Just throw on some plain, simple jeans and add on that beige blazer with a neutral color dress shirt.
I like this color combo (sea green over navy blue) over dark denim, sweater needs the heathered knit, not solid if wearing a non traditional color. J Crew style, sea green cotton sweatshirt worn over blue checked shirt with denim.