It will be 60+ degrees today, yay, but time for my annual transitional weather sartorial crisis! Whee.....

I rarely wear short sleeves, if it's over 70 I'm in sleeveless, below about 60 in long or 3/4 sleeves. I only own 3 including my work issued shirt, but there's got to be better choices, cause I feel like a big box when I wear them.

I was wondering if there are some that may look less frumpy on me than others- diagonal sleeves, a different neckline? Scrap it and just wear half sleeves instead?
Any ITs out there that have solved this?