Interesting...

Quick update...

After some advice from a friend of my wife, who used to be a professional plumber, I went home and checked the fixtures in the kitchen and laundry room. As he'd expected, they were VERY clogged with all sorts of gunk...probably a combination of rust from the old lines and dirt I introduced into the system when I ran the new lines. After cleaning the gunk out of the sink faucet aerator and the washing machine supply line screens, I have pressure! SWEET! Not quite as much as I had originally, but what I have now is definitely acceptable. I'll probably disassemble the sink faucet when I get home this evening to see if there's more gunk inside the fixture itself and see if I can increase the pressure a little more.

Unfortunately, however, I still have a problem when I try and use 2 things at one time. When I turn on the sink, and then turn on the washing machine, the sink pressure is reduced to almost a drip. Have to think about this a little more...

Anyway, more good news and bad news. It's starting to look like this might not be as catastrophic as I'd thought. Maybe now I can just concentrate on the kitchen situation rather than trying to redesign the whole system.