My default summer outfit (like 99% of the female population) is a lightweight dress that is well-accessorized. You literally can't go wrong with this combo, and it's super comfy to boot. I know maxi dresses are all the rage, but I'm pretty sure it will take Rachel Zoe herself to get me out of anything mini. (Ok, so maybe I bought my first maxi dress the other day, but still, ain't nothin like showin' a little leg).
It may not be the most fashion-forward outfit, but a simple cotton dress like this one from Old Navy can be paired with some bangles, big earrings, and gladiator sandals for a look that's summer chic.
If you wanna step it up a bit, look for more detail in the dresses you buy. This floral contrast dress from Evans has a sweetheart neckline and pleats that add interest.
This is the perfect example of that whole fashion/function thing. It's so easy to just throw on and instantly look stylish while still keeping cool. Plus, it can totally transition from day (big bag & flats) to night (clutch & heels). It's definitely on my "to buy" list. (It may be worth mentioning, however, that most things on that list are never purchased due to a severe lack of funds).