As far as pausing is concerned, I've used it quite a few times myself for a variety of reasons, and I usually try to time the pause so the head stops during infill or support printing, that way, there are no marks or ugly blobs in the print surface.   

I usually hit pause, then quickly hit retract 2mm, Z down by 10mm and X home.  This moves the print head out of the way so you can have access to the print or to the print head depending on what you want to do.  Then just prior to un-pausing the print, extrude about 10mm of filament to makeup for the retraction and any oozed material, remove the extrusion and restart.

You can also create a script that does all this for you when you pause the print.  In Repetier, on the G-Code Editor tab there is a drop down menu.  One of the options is called "Run on Pause" put your script with the code there and every time you hit pause it will automatically execute the codes for you.  The only problem is that I can't seem to save this as a setting, and when I exit Repetier it looses the script, so I have to do it again.

NOTE:
When you pause the print, Repetier keeps the head and bed heated to regular temperature.  If you plan to keep it paused for a long time, you can turn off the print head (extruder), but if you turn off the bed, the print will probably pop off.  You might try experimenting with lowering the bed temperature down lot about 50°C and see if it's still holding it in place, then when you're ready to start again, bring the bed temp back up.

Another option would be to kill the print somewhere at the end of a layer, then look at what layer you did this and edit the code to remove all the code up to the next layer, and start the print again.  The print should start on the next layer.  But again, you'll still have to deal with the heaters and so on.

You could also segment your model and print it in sections.  Use netfabb to cut it, then slice and print both halves as separate pieces, then glue it together.

TiM

Thank you for the tips. I am trying to reduce the time by changing the design (adding cavities, shells, etc), but it is not working. Even when I reduce the infill to 0.6, it still tells me that it will take 7.5hrs to complete!

Thats not an unusual print time at all for anything more than a basic model. I regularly do 8-10 hour prints either overnight or during the day when I'm at work.

I'd just let the thing print.. thats what most people do with long duration prints (i.e, ysb, who regularly does 8+ hour prints )

You don't have a woden frame like an old replicator/thing-o-matic... so the paranoia levels are not neccesary as the metal frame wont overheat and spontaneously combust... and the electronics are fused so there isn't a major concern there either...

One thing however is that if you are doing something in ABS or even PLA, you might benefit from leaving the bed heater on.  Cooling the bed might pop your print off, or at least weaken its adhesion.

Yes this is true! Turning off the bed will cause the print to pop off when cooled.
IMO pause use is more for short breaks in printing. Like changing filament.
Not a go and come back later thing.

Ii possible workaround is to change your settings to shut things off (heaters & motors) when job is complete. That way it's just sitting there waiting for you, finished when you come back. It'd only using a little electricity for the LEDs and printr board, instead of powering the heaters for hours while it sits idle.

Not quite you were asking for, but getting at the idea of what I think your goal is (to be able to manage a large print over several hours.)

One thing however is that if you are doing something in ABS or even PLA, you might benefit from leaving the bed heater on.  Cooling the bed might pop your print off, or at least weaken its adhesion.

I have a fairly large print that will take just over 7.5 hrs to print. I want to be able to pause the print, turn off the heaters, then come back turn on the heaters and continue printing. Is this possible?

I did the above but when I came back and I turned the heaters on the temperature did not rise and so I was not able to continue the print. But I also clicked on 'stop motor'; I don't know if this had anything to do with it.

Any insight is much needed.