Recommended Resolution Size for Project

There is no hard and fast rule. I'm partial to 1470 x 900. It's the same aspect ratio as 1024 x 627, but when your content is converted to a series of images, you end up closer to an HD quality slide than the default. You can try launching http://howbigismybrowser.com/ on typical devices used in your organization to see what numbers you get minus the browser elements. Selecting HTML scaling with the 1470 x 900 gives excellent results on most device screens.

There are lots of variables to take into account:

• Screen resolution
• Display percentage (not the same as above)
• Whether you will be using an overlay or static TOC
• Browser 'chrome'
• Windows Taskbar height allowance

But if you are working out this initial size for an organisation that consistent standards for recommended screen resolutions, then you can start by taking a screenshot of a web browser on your own 1920x1080 screen and using a graphics editor to remove everything around the center area where your course module would run.  Then work out how close to this margin you really want to go.

Once you have something worked out, create a test module at that size, with your TOC and playbar (if applicable) and then test it out on some coworkers across the organisation to see if they experience difficulties with scrollbars appearing.

For one recent client we found that due to a large number using display percentages greater than 100% the size of the Captivate module that worked most reliably was 1200 x 675.  This allowed everyone to see the content (with a TOC width of about 300 pixels) without scrollbars.

But your mileage may differ.  So work it out and test.  You do not have to use only the sizes Captivate provides by default.  Work out a Custom size and then set your starter project up for that.

You are talking about a non-responsive project, which is not published with the option 'Scalable HTML'?  

Do not forget that aa course will be playing in a LMS or a browser. Their UI needs some px as well, which you need to take into account. Same with the playbar and eventually the TOC which needs space as well.

Increasing the resolution of a course will increase the file size as well. That is not a problem if your audience all have high bandwidth and you don't expect them to use the course from mobile devices. 

Your question was very valid years ago, but has not so much sense nowadays IMO. If you want the course to fill the screen, and you are sure which browser and/or LMS will be used, you could figure out the correct height/width ratio of the free space in the LMS or the browser (if launched from a webserver instead of LMS) and choose a course resolution which has that same ratio height/width. Publish it to Scalable HTML and whatever the used desktop/laptop screen it will be displayed filling the screen. If you expect use of mobile devices, create a responsive project where you apply the same rule for the desktop resolution.

Probably not the answer you expected, but just asking for a one resolution answer is bit outdated. Of course most screens are now in 16:9 ratio, but every LMS will need its specific extra space horizontally and vertically.