I'd tend to lean towards the .243win if it can serve double (or triple) purpose for you.

A .243win could take the place as your go-to deer rifle, could be your go-to coyote rifle, and could be your wife's deer rifle...

A 223rem would be my second choice, dedicated coyote rifle, but it wouldn't have as much versatility as the .243win.

I have much love for leverguns, but I'd go after a different cartridge than 30-30, since you already have a 30-06. 44mag or .45-70 would be good options. And when it comes to leverguns, remember the 3 M's - Make Mine a Marlin!