Open Safari With Numerous Tabs Open?
Yes, but the sites you want to use must be saved in a folder in your bookmarks.

Once you've bookmarked the sites all in the same folder (the only contents of the folder should be these sites), go to Safari -> Preferences -> General. Click the Choose Tabs Folder... item in the New windows open with: menu and select your folder.

New windows will open with each of your websites in tabs.