I've got a couple sets of the $9 Duracell -branded sets from Lowes or Home Depot; they're cheap enough that I can stick them on the kids' bikes, and the 2x AAA provides good runtime and shelf life, especially for occasional use.
I have some of the Stupidbright micro -blinkies on almost all of my bikes for the times I might get caught out late, or decide to ride with the Dawn Patrol. Same thing: They're unobtrusive, and seem to always be ready when I need them.
I'm not a big believer in Daytime Visibility Lighting ; I just don't think a typical bicycle light has a large enough reflector to be visible in vehicle traffic, or from long distance unless it's really, really bright , like police car bright; and while such things exist, they're really too expensive for something that's a supplemental measure at best