One water heater...or two?

[GaryS]

Our current house is a single story with a lot of sprawl, so it has two electric water heaters. One is in a room off the kitchen and guest bath. The other is on the opposite end of the house and services the master bath and utility room. It's located in the attic and is supplementally heated by water circulated through the geo-thermal heating and cooling unit. The distance between the two water heater is about 60'.

We are now in the process of making plans for a new energy efficient house that will be very similar in design to this house, but we're unsure how to spec the water heaters. They will again be electric, but I'd like opinions on how to set it up for the best use of energy. Would you use one heater and circulate the water, or would you use the current two heater setup, or would you opt for a tankless heater in either or both locations?