Well, one reason for asking the question was to weigh the cost of buying
more tools, compared to having an electrician do the work. I just called 3
electricians. Holy smokes! They all said that if the jobs were nothing
unusual, I could expect to pay $200-$300 per room.


.... and I've seen people pay good money for work that I sure wouldn't be
proud of.

.... and while they do have an assortment of tricks & experience snaking
wires behind walls, they have limitations too. You might wind up doing
a little plaster / drywall repair no matter what. (Or you might luck
out, too.)

You might consider one of those Time-Life DIY books on home electrical
to get a better idea of how to get the job done. They're great books,
well thought out, and could easily pay for itself.