Since your bathrooms are small, a double lamp (bulb) fixture over the mirror will suffice. You don't need a lighted ceiling vent fixture. Overhead lighting in a small bathroom is generally the wrong type, since it is of little use to someone at a lavatory and mirror.

Those mirrors are only 300 lumens output so they aren't going to light the room. I would rather have too much light than too little, especially if you have switches for each fixture.

As @Lyndee Lee pointed out, these mirrors produce 300 lumens, which is the equivalent of only a 40 watt bulb. These are meant for accent lighting, not task lighting. For both baths, I recommend additional sconce lighting. Also, a Solatube is great for the daytime, but at night, the shower will be dark. I recommend additional recessed lighting in the shower.

In general, for very good vanity lighting, I prefer sconces flanking a mirror instead of lighting placed above. I aim for over 2000 lumens total per mirror (dimmable) and a color temp of at least 3000k (the mirrors are 2700k).

@Kristin Petro Interiors, Inc. Thanks. The vent fan in the primary bath will be near the shower, so I'm perfectly happy leaving it at that, but I will be sure to have sconces above the mirrors. We had this mirror in our previous house with a vanity light over the mirror (one light, one mirror) with no additional lighting in the bathroom and found it to be sufficient, and when standing at the sink, the light was wonderful for getting ready. I personally quite dislike cooler color temps, so am happy with the 2700k.

Buy fixtures that will accommodate different bulb wattages and lumens.

@Mark Bischak, Architect Thanks! We are definitely planning to do that. All lighting (with the exception of these mirrors because we have used one before, like the color temp, and they're cheap) going into the house takes standard bulb sizes so that we can swap things around if/when we want a change in color temp or brightness.