Personally if it was me, I would go with the PVC for right now. I would use the 3/4 inch plastic for "volume" since you have enough pressure, that way, you would be able to flush the toilet, run the washer and still have enough for filling the tub, or taking a shower!
Scab that in first, (that is, if you can afford it, if not, then scab in the entire 3/4 lenght of copper in besides the old, or even put it in places that will be a better place, or where you "want" the thing to be, this time, because it will be your last chance to do it.
Its what I did, and I put in extra valves, so that I could shut everything off in the basement, as well as under the sinks and toilets.
Mapp gas is great for 3/4. But, when I did mine, I "tinned" everything first, so I was assured of every solder joint being a good one! (didnt have a single leak because of that!).
Also, I would run the 3/4 up to the floor, and go with plastic from there, to your appliances, so that its quicker and you wont be "down" long. Toilet first, then sink...(This being only the COLD water line, the hot water line would come in later, as I still have to change my hot, but all my cold is 3/4 and I am sure glad that I did this!).
Just a quick suggestion...
Oh, with water in the lines, forget about trying to "solder" anything! You have to first boil out the water, and that takes time. Get a wet & dry vac, and a long tube, so that you can suck the water out of the line if necessary, or, even put some hose bobs in several locations so that you can drain some lines if you ever need it. (I have one next to my water meter, so that I can drain it to take the pressure off my whole house water filters, when they need changed).
Ok, 'nuff of my rant and rave...
Jesse
Jesse