How big are you, and how can you normally dress?
Several months of the year I can wear jeans with a windbreaker or sweatshirt most places besides work, and I can comfortably conceal a 4" Python or a 5.5" bull barrel Ruger Mark II. But I am a bigger guy, lots of folks can't do this.
The hottest part of summer, it has to be something I can carry in my pocket. Even the SP101 might be a little heavy.