In case you haven’t seen or used it, there is a “Bulk Actions link” just under the “Add Monitor button” in the left sidebar.
It simply opens the “Bulk Actions dialog” and presents a set of actions that can be applied to monitors in bulk.

This feature is now more powerful with few important additions including:
- support for maintenance windows
- support for SSL settings
- applying the actions only to selected monitors (besides all monitors)
- choosing to overwrite or apply by preserving the previous settings
Hope that they will help and we are already working on the expected addition.. which is “bulk importing monitors” :).