Currently, the Wiki reads:
The Rest Area Place area should be covered by a landmark, drawn to the borders, and along right-of-way of the adjacent highway, but not snapped to the highway, and should not cross a highway if the rest area is on both sides. A landmark type of "Transportation" should be used. The landmark should be named as follows, using the highway name and cardinal direction as part of the name for POI search purposes: "I-10 W Rest Area", "Pennsylvania Turnpike E Service Area" if commercial restaurant/fuel is offered, or "Tennessee Welcome Center" for official state welcome centers. If the rest area is given a name by the state D.O.T., it may be used, e.g., "Dizzy Dean Rest Area".
The problem I see here is that in the new Places hierarchy of Place Types, "Transportation" is a parent heading with sub-types under it. I'm not sure if it's even a valid Place Type without selecting a sub-type.
There's no good sub-type under Transportation, and I'm not sure that Transportation is even a good type.
My proposal would be to use the "Park" type, which would make it stand out a bit on the map, and a Rest Area probably more closely fits the definition of Park better than anything else.