Problem Statement
Unit converters in Calculator support a large set of units, which can make it difficult to quickly access common or frequently-used units.

Evidence or User Insights
There is some discussion in #382 regarding having a smaller set of units by default with an option to turn on more in settings. Numerous issues (#108, #167, #271, #325, #275, #515) discuss expanding the set of units or converters further, which improves converters overall, but makes this particular UX problem worse.

Anecdotally, it is clear to see some scenarios where we show common units mixed in with uncommon units:

Proposal
Update the unit selection UX to highlight common and recently-used units and make it easier to find and select units.

Goals

• Users can quickly select commonly-used units
• Users can quickly select recently-used units
• Users can easily find less commonly-used units

Non-Goals

• Determining which converters/units to include is out-of-scope (covered by Converter should integrate (or reuse) online unit conversions (Bing or similar services) to increase category/unit coverage #515)
• Redesign any other parts of converter navigation or UX

Low-Fidelity Concept
One approach might be an AutoSuggestBox/ComboBox hybrid experience. This would allow us to highlight the most common units as well as recently used units, while also allowing users to search-to-filter/select any unit.

_{Instead of People/Places/Things, we could highlight common/recently used units}

Requested Assignment
I'm just suggesting this idea. I don't want to implement it.