Many boards come with a built-in LDO (for example, the Artemis boards like Artemis Nano). This is convenient as it allows to plug in a battery with voltage equal to vmin = 3.3V + dropout of the LDO, or higher, but it is also quite a limitation: it just dissipates the “over voltage” as heat, so it is power inefficient; it does not adapt voltage that are lower than vmin, which can quickly happen during bursts of power consumption if small batteries are used; if having access to a “nice” 3.3V supply, this will not work, as the minimum value is vmin.
The solution I personally use is to systematically plug in a pololu 3.3V step up step down converter, like this one, on the 3.3V power rail: https://www.pololu.com/product/2122 . Cheap, efficient, simple. Sparkfun has a similar product, but with higher minimum input voltage, bigger, and needs a bit of setup since need to choose the level: https://www.sparkfun.com/products/15208 , or this cute little thing, but only step down: https://www.sparkfun.com/products/18357 .
My question is: is it not time for these poor LDOs that get thrown on many boards to end? Have not these step up step down converters become so good and cheap that it would be possible to include them by default instead of LDOs on SF boards? Ok this may add a USD or two on boards (not even sure though, as if these would be added on many boards, the economy of scales would probably make them really cheap to add), but this would solve many power issues people meet, avoid the need for adding external regulators for those who operate from batteries, make many boards much more “semi professional use ready”, etc.
The set of useful features would be:
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accept inputs in at least the range 2.5 - 9V, so that everything from 1 semi depleted cell to 4 AA Li cells can be used
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have a quiescent current as low as possible to make the board “low power friendly”
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have a small pad or similar to be able to turn on off
I think that this would make sense on many of the affordable SF boards, and definitely would be a big plus on the expensive boards (SF Artemis Global Tracker, looking at you 
).