For people whom you regularly communicate with, just check the star to the right of their name after clicking on them as a contact, and they will be added to your "favorites" list, which is easily accessible for phone and mail.
For using google contact groups, first sync all contacts between droid and google contacts, and divide google contacts by groups, which then appear on the droid, by going to menu, contacts, display options, google. Your default position could be to only check system group-my contacts, and none of your other groups below. That way you see all contacts when hitting the contacts button.
When you get into display options google, you could then disable the system group check, and just enable one of your other groups, which will result in only that group being displayed after you return to your contacts page. Alternatively, you could have no contacts checked, including system group, but then see no overall list, and everytime have to go into your groups and check one in order to see its members.