I doubt many would think that a 125 is too small for most planted tank purposes. Your mistake is putting it too close to the giant. Spread out a little; your floors will thank you.
As for the new 180g six footer: I share your excitement! A big tank is LOTS of work to get started - at least mine was - but once up it is a pleasure on a scale few get to enjoy. Two that size will make a nice room.