If I am casual, a sweatshirt.
Corporate casual....a sweater.
Business attire....sport jacket.
Summertime....think of something not tucked in and carry IWB.
I buddy of mine has to wear a polo style t shirt for work, tucked in...so he carrys his secondary CCW, a snubby S&W38 in an ankle rig in loose pants.
A vest can be a warm weather option, but I am thinking Florida summers are a bit more than just warm