Can two play at this game?
Don't forget that at most stores like BB or CC, if you buy an $1850 display, you'll also need to allocated about $250 for a stand to put it on. You can get close to 60" in a plasma, but I doubt for $2k. I don't know if you can even find an LCD at that size, surely not for $2k. So you're pretty much asking for a rear projection set - DLP or whatever.
I've never seen an LCD that approaches the PQ of my current display (even though it's only 1080i)
1080i vs. 1808p - terribly overhyped. But pretty much a moot point anyway. You will find it very challenging to find any new 60-65" set that is not 1080p. I'll bet you can't.
Also, plasma has issues at high altitude? I'm at 4200'.
They sell them here in the Mile High City without problems. We've got a 1000 feet on you!
DLPs look OK, but I read about a "rainbow effect"
"read about" means nothing. Can YOU see it? Probably not ... most people can't. I don't think it's a big concern these days. If you go by everything you read, you won't buy anything. Plasmas a bad because of glare. LCDs because of motion blur. DLPs because of rainbow effect. Read about everything, and you have limited yourself to a choice of ... nothing. When I was shopping, I tried and tried to detect motion blur on the LCDs. I couldn't. I tried and tried to see rainbow effect on DLPs. I couldn't. I was able to see the glare on plasmas though. Whether that would be a problem for you depends on the displays location in your home.
The choice will have to be yours. What I like, you my hate. What I found is that I initially stayed away from DLPs. I thought they looked terrible compared to other technologies. Kind of grainy and washed out. But what did I end up with? A DLP. And I couldn't be happier. Seeing it in my home instead of a showroom is like night and day. The picture looks fabulous in my house. MUCH MUCH better than what I was observing in the showrooms. It replaced something that sounds similar to what you are replacing. I had a 10 year old Mitsubishi 60" CRT rear projection. Two large upright refrigerators side-by-side would take up less space than that beast.
For reference, I ended up with a Mitsubishi 65" DLP. Model WD-C657 from Costco. It was $1700 including the stand. The WD-C657 is about halfway between Mitsubishi models WD-65733 and WD-65734 in features, except it only has two HDMI inputs and two component inputs, which still meets my needs. I was initially about to buy a Panasonic 58" plasma, TH-58PZ700U, which was more than double to cost of the DLP set I ended up with.
I would recommend shopping around quite a bit. I went everywhere from ListenUp (a higher end store) to lowly Costco. If you're like me, you should expect your thoughts to change multiple times. Try to look at the same set in different showrooms. You might find what looked so impressive at one place may look not so good at another. Or the opposite.