I would like to ask webmasters, what optimal website page sizes are?

Theoretically it should be liquid layout, but this has it's disadvantages, mainly it restricts your design, also liquid layout should be optimized for a minimum width as well.

So instead of optimizing it for minimum width, why not use fixed layout?

I personally go to 960px (number that can be easily divided into many grid sizes)
The audience is important as well, if I expect my visitors to be mostly elderly or will be using older browsers, then I go for 744px

I personally make all my stuff fit on a 1024x768 screen with a liquid layout, so it also fills up the screen on larger monitors, I hate when I go to a site and its a fixed layout and I have 6 inches of screen on each side that is not used.

I find it a lot harder tho to make it fill a large screen, as well as a small screen and look good.

I just wish people would get bigger screens. :D

I do essentially the same as WebNaz although I haven't settled on an exact width, just something in the ballpark of ~50px below my target resolution.

After having designed some liquid pages that looked good at 800x600 and 1024x768, then upgrading to a 1600x1200 LCD screen and seeing my designs look like crap, I decided fixed layouts aren't so bad after all, even if I'm looking at half a screen of gap.

"fixed width" designed for 1024+ would be the best for most visitors.

lots of usability issues for liquid layout. for example it's very hard to read with variable-width main content in 1920 monitor or even higher resolution.

you should build in a fluid layout to avoid this issue. As there is some variation in screen sizes to accomodate.

Fluid layout should be your first priority. However, if the client or you feel that going with an aesthetically pleasing design would be more appropriate, you should decide what your user base would be more comfortable using.

If your userbase is not specifically under one group, you will probably want to make sure it fits on a 1024x768 screen. You no longer need to fit for 800x600. I don't think we'll be moving up from 1024 for a little while, because of UMPCs and the like, but you never know.

If your userbase uses a minimum resolution, such as those you would find on a closed-network web portal, it would be safe to set it at that minimum resolution.

I highly recommend a fluid layout. Non-image based design can go a long way (not as far as image, mind you) and a fluid layout offers a lot of advantages for differing resolutions.

I personally go to 960px (number that can be easily divided into many grid sizes)
The audience is important as well, if I expect my visitors to be mostly elderly or will be using older browsers, then I go for 744px

I agree with this. Few years ago, probably width for 800px monitor was the favorite. But for now, I think I'll stay waith 960.

But, I think sometime it's not only about the "best width", it depends on the site contents too. I like having 960px and divided into 3 columns since I can put more contents there. :)

A case by case basis is best. I build every web application specific to my client. My first stop before I even start a layout is to their office where I suprisingly usually find 17-19" monitors with a catch. They often run them at 800x600 resolution! Of course the first thing I do is show them how to change the resolution or increase the font size but most will still change it back. For those situations a 760 fixed or a liquid min 760 max 990 layout work best.

With the ever increasing popularity and affordability of 22"+ monitors you also must remember that not everyone maximizes their windows. This simulates a dual monitor setup with only one monitor. JM2C FWIW.