Wearing a blazer with jeans is a great way look elegant but, at the same time, casual. A blazer and suit combination done right is a very versatile outfit, which you can take from day to evening and which you can easily dress up or down.
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.