Seems it will be easy and relatively cheap ($350) for them to drop 4 20-amp circuits from my breaker box to 4 new outlets directly below it. This would give me a lot more flexibility with my current setup (rigs in 5 different rooms), as well as the ability to more easily expand to at least 7-8 rigs. Each of those 20-amp circuits could take 2 of my current rigs since they only pull about 800W each, so would be well under the recommended max of 2000W per. Then I would just need to plan out how to best distribute my newer 7-8 GPU rigs, but overall, this expansion will make things much easier to manage.
The only downside is that my garage has no natural ventilation and while I can run 1-2 rigs in there from Oct-April/May without it, I will need to come up with a solution for more than 2 and/or in the summer. The electrician seemed to think it would be relatively easy to buy a portable A/C unit and hire someone to drill through my wall to vent it outside. I was originally opposed to this idea but if it's pretty common and easy to do, I would of course consider it. Any of you go this route with your setups?
An ac unit will just drive up your power bill - what you need for mining is to vent that hot air out, not try to cool it down with AC (which won't be able to keep up anyways if you get several rigs in there. Install a commercial grade exhaust fan, think of what is used in greenhouses for example, and if possible have an open window or vent in a door etc on the other side of the room.
We have a room in our barn with 12 rigs in it and the above method works very well for us, even in the summer months.