Would it be a worthwhile investment of time and effort to create multiple starting villages?
Or a mechanism to allow players to do so?

What would be a good recommended minimum and maximum size for a starting village floor plan?
Working on a 4x4 chunk zone in a superflat world at the moment.

@WildBamaBoy why cant you initiate a vanilla village? it would adapt to terrain and be random. does anything limit it to being created at worldgen?

Well, the vanilla village's idea of "adapt to terrain" can leave something to be desired. Take a look at some of the villages that spawned over ravines, water, or uneven terrain for examples (especially when they extended over the border to a bumpier biome). I've seen some especially spectacularly broken villages in Abyssalcraft's Darkland Highlands -- I think that moddev has since disabled villages the Highlands, but I got another groaner when a desert village extended into "ordinary" Darklands.

still better than flat plane that overrides everything.

Sure, I can add them easily if someone wants to build them. A mechanism for adding them manually, though, not so much.

It'd be kind of cool if we could leverage the MCEdit schematics files. That would provide a convenient import/export mechanism... just a thought.

IIRC, the MCEdit schematics don't allow for adaptation to terrain. The Ruins format does have some ability for that.

OTG has some nice way to create custom villages with very custom structures. Maybe it worth to take a look.