For most desktop users, a 17" CRT is nearly ideal; it's size and weight are manageable and they are inexpensive.
As for image quality, it's hard to argue a CRT is deficent in this area. However, it is strange that about 90% of CRTs sold are el-cheapo units with marginal image quality to begin with, you have to wonder why people even bring it up.
I spent the extra hundred bucks for a good 17", but at some places it's even hard to find a good monitor for sale.
20" and larger CRTs are a different story. They are huge and heavy, and quality monitors in this range are not inexpensive. The new 20" Apple display compares favorably with CRTs and comes at a price premium that is closer to 50% than the 200% it was just a year ago. I have to say my crystal ball says that bigger LCDs are going to take this market by storm.
Screen speed is becoming less of an issue; 25uS or less is common now and some are getting 10uS, which is the point where it's a non-issue. So, if there are images which can tax a screen today, it's not going to be that way for long (and it's debatable if current ones can't keep up).
So, in my humble opinion the 17" CRT is going to be around a while, and some might even put up with a 19" model, but LCDs are going to replace bigger monitors on the desktop.