If you find yourself often opening the same windows, tabs, and documents often, it can be a bit cumbersome. Similar to a concept found in applications like Adobe Illustrator, there is an option in DEVONthink's Go menu: Workspaces. From the Documentation > Menus section of the Help:
Workspaces save the content and positions of all open windows so that you can restore them later. This is ideal if you are working with the same set of windows over and over again. Save these windows as a workspace and recall them whenever you need them again.
To create a workspace, open the desired databases, windows, and documents. Arrange the windows to suit your need, then select Go > Workspaces: Add. Give the workspace a name and you're done.
As you work in DEVONthink, you likely open new windows and rearrange things. If at some point you want to return to the view you had, you can select the workspace from the bottom of the Go menu (or press Option-Command and the number of the workspace, if you have several).
Note: This will open databases as needed but will not close currently opened ones.