HubSpot Target Accounts is a function you may want to start using.
This allows you to edit a custom list of your Tier 1 – 2 clients so that you can easily track them in one place, and also engage some of the more in-depth features to focus on those accounts. It’s also just a nice way to tidy up your customer list and put the more important accounts in front of you.
Here’s a video to help you set it up, It should take less than 5 minutes.