I found a place, so I thought it might be helpful to some others if I describe to what extent I succeeded (or failed) in finding what I was looking for.
I want a two-bedroom place (three br is OK), one or two bath. It must be furnished and have at least a refrigerator and stove/oven. A washer would be nice, but I can probably find a laundry somewhere. A dryer would be heaven, but if there's a place to hang clothes, I'm OK with that.
Mostly got what I wanted. Found a 2br/1bath place, fully furnished, with all appliances including washer/dryer and even (bonus!) a microwave. The only things I've had to buy are an electric teakettle and towels/bathmat).
Either Centro or Norte is OK. Of course, I want to be near shopping, and I'd like to have a park of some kind nearby (I enjoy running and biking).
I figured I'd end up in Norte when I wrote the above, and I did. I'll be a10-12 minute walk from Quicentro and maybe another five minutes from the Megamaxi on 6 de Diciembre. Of course, Quicentro is across the street from Parque Carolina, where I see joggers/bikers out all the time.
I like much about Centro Historico, but there are a lot of inconveniences here. There are always trade-offs. Perhaps I'll change my mind after a while in the north, but we'll see.
My tentative budget is between $400-$600, and of course I'd like to be on the lower end of that range ...The rents I'm mentioning are all-inclusive a place that didn't include utilities or condo fees in the price would need to be correspondingly cheaper.
I ended up on the higher end of the range -- $570 -- oh well. Got a six-month lease instead of twelve, so I can look around and find something better if I decide this is a poor deal. My rent includes everything but electricity -- gas (the complex has central gas, which is a positive), water, cable TV, internet, condo fees/24 hour security.
On the downside, the place is small -- fine for me, but I expect visitors from the States and it will probably be cramped when that happens. Also no views; in a city with such a beautiful setting, it would be nice to see the mountains from my living room -- instead I'll be looking out on the complex's courtyard. All the more reason to get outside, I guess.
Bob