I have currently 17" in SXGA, and I used to read a lot of PDF files. What I want pages should be displayed in book view (double full page). Is 24" in 1900 x 1200 enough to display PDF, since in this mode while keeping the text big enough to be read from about 60 CM or more ? If not, what sizes and resolutions are the best suitable?
If you want to display your documents at real size, you'll need a monitor with a width of more than 42-43 cm (for A4 and Letter pages).
I have a 21.5 inches 1920x1080 monitor with a width of 48 cm and it is good for this. The height of 27 cm is however not enough for the 29.7 cm of A4.
keeping the text big enough to be read from about 60cm
That depends a lot on the text size and font.
Is a 24" in 1900x1200 enough
I would say yes. It would have a width of 20 inches (51 cm).
The recommended distance between your eyes and screen is an arm length.
The arm length is around 60 cm (25 inch). At that distance, the x-height for easy readability is 3 mm (2 "sub-inch").
The page width of a textbook is usually around 20 cm (8''). To get a 3 mm x-height of text, the page needs to be zoomed at 200%, or 40 cm (16'') width. A 18'' monitor can satisfy this.
Note: my textbooks have one main column and a smaller column for note-taking, and I don't need double full page. So this doesn't answer OP's question, but it may help other visitors.
An example of such page design, taken from Strenberg, Cognitive Psychology: